I will assume that if you are here, you already checked the official documentation, Microsoft forums and maybe even a few more websites that looked promising but you got no real answer. The same thing happened to me and I had to dedicate a few full hours to research why and how could I delete a calendar that has delete option grayed out.
Now, if by any chance you didn’t do any of the above, so you skipped losing your time and you just got to this website, Kudos to you, as you saved a few hours of search and you got to the right spot, assuming the title and what you are trying to do is what I am actually presenting in this article, and it is not just failed pointer from Google based on some of the title words.
There is no way to explain this with too many technical details and I can’t even get too deep on it, as many of the causes and even an official solution still lack. It might even be a bug or an option not very well implemented by Outlook/Microsoft developers. I can provide a way to manage to do what you are trying, better say, a work-around fix than a real solution (note that asking for help on Microsoft might let you with no answer, as it did for me). If by any chance any of you finds out more about this, why does this doesn’t work, or of another way than the one presented in here, please share it with us, but do test it before, don’t just throw it in here after you read a few forums, as I can assure you that at least 90% of the documentation and guides present on the web even remotely linked to this subject, I have tested them and nothing worked except for what I am about to describe below.
There is no easy way to do this, like for example for those of you searching for a registry key or a representation of the Calendar file somewhere in the Outlook installed files, you will be disappointed. The actual Calendar is somehow embedded in the .PST or the mail file you are using, as a feature of it or a tag. There is, however, a bypass or a work-around but only if you are willing to put a little bit of time into reading and if you are willing to accept a compromise, else this is not the right place for you, nor will this help.
First of all, you should know that when I speak about Calendar Menu I speak of the one located under Mail Menu (Options/Window), the one located on your bottom left corner. When you click on Calendar, the Menu expands and you can see a list (if more than one Calendar present) of calendars, as you can see below:
You will always find on first place in your Calendar list, the one set as default (associated with your DEFAULT mail file, whether it is a server mailbox or a .PST file) and you can call this option even as inherited as it is directly associated with the mail file you are using. In my case, when I took the above screen I had as default e-mail file, a Personal Folder(s) file that automatically made the Calendar associated with it appear as default in Calendar Menu, which also reflects the fact that you see it on the first place in the Calendar list. The second one for me it isn’t in fact a default one as you can figure it out, but it is the server mail file.
I should also cover the fact that if you are not dealing with Personal Folder(s), you won’t have such problems. If using only the server mail file you would only have a Calendar, also displayed as default, without any list, it wouldn’t even be displayed in Calendar Menu as a list, it would just open up your Calendar.
The thing is that due to several reasons, those of you who came here for the actual problem that we will try to fix, have also to work with Personal Folder(s). For me it is the size on the server mail box which has a limit that can be easily filled up, and then the annoying warning to clear the mailbox will popup. In some cases when the server mailbox is full, even worse things can happen like for example the fact that you won’t get any new email until you make some space.
So, if you or the user you are trying to fix this for has Personal Folder(s), you will see the Calendar list in the Calendar Menu. In those cases when they have even more than a server mailbox and a single Personal Folder(s) (.PST file), you will see them all in Calendar Menu, in the Mail menu, plus they can be found in Tools – Account Settings – Data Files.
The fact is that if you are trying to delete some of these Calendars, first confirm with your user, which ones he doesn’t need/want. For most of them it will work just with right click and “Delete”. At this point you are left with TWO Calendars, one being the server mailbox associated calendar and the other associated with an EX (you will see soon why this calendar can’t be deleted even if it is not marked as default anymore) Personal Folder(s) (.PST file). I should also mention that for those Calendars that you don’t have the “Delete” option active, which is instead grayed out, you will also lack the option to “Rename” or “Move” because it will also be grayed.
I am sorry that I can’t make a simpler solution about this in just a few steps but it is a bit tricky so you will have to read and execute the instructions below as they are. If any of the actions are not made correctly, this won’t work.
SOLUTION TO DELETE CALENDAR:
If this is not made for you and it is made for a user, both of you have to understand the fact that if you only want to have a single Calendar in Calendar Menu with the sole PURPOSE of having both sent and received information (appointments and meetings) in the same Calendar Entry, you will have to use the server mailbox as default mail file. This means that all of your emails will be received on the server mailbox, so you should take in consideration and check again if this is possible, keeping in mind the first causes that made you use Personal Folder(s) and the available space. In other words, this can be possible, if for example, the space is limited and you only have a given mail size box, if you will use the Personal Folder(s) as storage. This means that you will either manually move the emails from server mailbox to Personal Folder(s) .PST file or via rules so you won’t trigger the warnings or even worse, block your mailbox with more than it can handle.
Note: If a Calendar has the option to “Delete” it grayed out, it could mean that this calendar is in fact associated with the default mail file, so this would be logic not to allow you, so think in changing the default mail file. If this Calendar is not associated with the default mail file, in normal conditions it should allow you to delete it, but due to a bug or a technique poorly implemented it doesn’t work like that and you will have to read the whole article to understand why.
Now, I imagine you have already noticed when you were seeing two calendars in your Calendar Menu (Calendar associated with server mailbox and the Calendar associated with a Personal Folder(s) that at least once was set to default), that if you send an invitation to someone it will be stored in the Calendar linked to your default mailbox file. If in this scenario you would receive an invitation from someone, it would be stored in another Calendar, the one associated with the server mailbox. The fact is that this is somehow logic, to have the sent on the .PST mailbox and received on the server, until a point that the invitations or appointments received on server should be automatically placed in your default mailbox (.PST file) associated Calendar, similar to the process of emails received on server but due to the fact that you have configured a .PST file, they are automatically sent to the inbox on the .PST file. This step doesn’t happen for Calendars, the entries will remain on server.
So, if you set the server mailbox as default, the Calendar associated with it will contain both sent and received appointments/meetings/schedules. The only problem left is that you still cannot DELETE the Calendar left in Calendar Menu and associated with the Personal Folder(s) which is not set as default anymore.
Some people at this step will decide it is enough and wouldn’t want to risk anything more and will just uncheck the Calendar and leave it in Calendar Menu unused. The risk is minimum in case you are wondering if to proceed further to try to remove it or not.
What you have to do to remove the unused Calendar entry associated with the Personal Folder(s) which is not set as default mailbox file anymore?
1. Create an empty .PST file from Tools – Account Settings – Data Files (Use Add and follow the easy steps: confirmation with “Ok” two times).
2. At this step DO NOT SET this new .PST file to Default, or else you will have to start all over again and create another .PST file.
3. Copy every folder and email you need from the old (faulty) .PST file – Personal Folder(s) to the newly created on at step 1. Do NOT touch the Calendar; do not save anything out of it to this new Personal Folder(s) created at step 1.
4. Use the “Close personal folders” option from right click selection on the old Personal Folder(s) in the Email menu, even if selecting it and using remove from “data files” in “account settings” would do the same. You can do it either way, it does the same thing.
5. Close the Outlook and open it again.
6. At this step you should have Server mailbox as default email file, and Calendar associated with it being the only one present (as default) in your Calendar Menu. You won’t actually see any Calendar in Calendar Menu as the server mailbox associated one’s Calendar is by default opened when you go to Calendar Menu. You will also have a Personal Folder(s), the one newly created which will contain the backed-up emails and data. You will have to manually move all your emails from server mailbox (if limited by whatever reason from storing them on the server, or if preferred by user) to this new Personal Folder(s). You can also create “Rules” to manage the copy/move of new emails from server to .PST file.
7. Do NOT set the Personal Folder(s) to default or the problem will be back. The minute you set it to default, a new Calendar will be displayed in your Calendar Menu, again without the option to “Delete” it even if you set the server mailbox back to default at this step.
What we can conclude from this is that the .PST file when set to default, it receives some data stored to whatever location, possible registry or a file somewhere in APP data, maybe even stored on the same .PST file as a flag or something. I didn’t find anything about this, but we can see it happen the very minute you will set it to default. You can’t revert back and you can’t delete the Calendar, without repeating the above steps on a CLEAN .PST file. It is either a bug and the .PST gets corrupted or the developers didn’t really implement this function well for Personal Folder(s) Calendars.
In case the steps were not clearly enough, I did my best to cover them in a more detailed example as you can see below:
I created a new personal folder .pst file from “data files”, let’s call it .pst(2), I moved the folders I needed to backup, folders with all my emails and info from the old personal folders (1), except for calendar, …didn’t touch that part.
I used the “Close personal folders” option from right click selection on the old personal folders(1), even if selecting it and using remove from “data files” in “account settings” would do the same. Close the Outlook and open it again and you will see only a calendar, for the server mailbox file left as default.
Now I have in my “mail window options” a server mailbox set as default and the new clean with the backup emails personal folders (2). There is only one calendar present in “calendar window options”, the one from the server mailbox. As long as you will ONLY receive emails on the server mailbox and if needed due to space or other reasons, move the emails to personal folders at this step, in our case personal folders(2), everything will work nice and smoothly. You will only have a calendar: the server mailbox calendar which now stores both sent and received appointments and data.
I wanted to see what and when this happens and it seems as soon as I set the new personal folders(2) to default, the whole process happens again: two calendars, no more delete option available on .pst, no matter if you set the server mailbox to default. At this step you will have another problem, the sent invitations and appointments are stored to personal folders, in our case personal folder(2) and the invitations and appointments received from other people are stored to server mailbox calendar. At this step you will have to use both calendars.
So the process of setting a clean .pst file as default adds the calendar option which is normal as I see it because it becomes your primary mailbox so it must support all functions usually provided by such a service, but according to what I above explained it is not correctly implemented or something.
The problem for me started with a user that wanted to have the same information sent/received in the same calendar, which is not possible of what I see if you use a “personal folders” as default. In this case, the calendar associated with the server mailbox will only store the received ( from other people ) information, while any information the user will add, for example an invitation to a meeting, will be stored on the personal folders calendar.
If this is how it should work, I guess the only way for a person to have only a calendar is to use the server mailbox as a default and a personal folders .pst which never had the “default” option set, as storage and to manually or use rules to move emails there from server, just in case for whatever reasons the emails are not to be kept on the server mailbox. If by any chance, you set the .pst to default for testing or a short while, even if you revert back to the server mailbox being the default email data file, it is too late and you will already have multiple calendars, and then you have to re-do the whole new clean .pst file steps.
I’ve tried fixing this from GPOs, registry, access rights, AD rights, multiple possible solutions via Outlook configuration and the files it stores during this process. If you find any other way please test it before or do mention it and I will try it out, as I am curious and probably others too, on what is actually happening.