You can't remove a calendar item such as a meeting request, a reminder, or an email message in Microsoft Outlook in Microsoft Office 365. Additionally, if you try to remove a meeting request, you may receive an error message that resembles the following message:
This meeting cannot be removed because you are the meeting organizer.
Note Before you try the methods in this section, exit all clients (such as Outlook and Outlook on the web) on which the mailbox is set up, start Outlook, and then try to remove the item. If the problem persists, try Method 1 first. If that doesn't fix the problem, try the next method.
To resolve this problem, use one or more of the following methods.
Method 1: Use Outlook on the web
Try to delete the item in Outlook on the web. If you can't delete it in Outlook on the web, go to the next method.
Note If you can't complete a task in Outlook but you can complete it in Outlook on the web, this might mean that Outlook has to be updated.