Deleting a meeting from outlook.
Sometime Old repeated meetings gets corrupts and it’s hard to delete them, when a user try to delete them they return back on the calendar.
Here is what you can try:
1. Open mailbox using OWA or you can directly open calendar using the below URL.
2. https://outlook.office.com/owa/?path=/calendar/view/Day ( this applies for O365 only you may need to change the URL if it’s on premise Exchange)
3. Now Open the meeting and send cancellation for the Series, this should remove all the occurrences from the calendrer.
Most of the time deleting meeting from OWA fixes the issue.
If meeting still returns then you need to try to more advanced user approach and you can use MFCMAPI tool to do hard delete on meeting.
Warning: when using MFCMapi tool do not delete anything unless you have tested the tool with a test mailbox and you are sure of what you are doing.