Hi @shaka ,
Has his account been deleted from AD for more than 30 days? If not, you could restore his account and cancel the meetings, if yes, then you could use the following methods:
1.Open calendar in outlook and double-click on the meeting - it should give you a popup asking whether you want to open "this meeting" or "this series". Choose the latter and in the following popup, choose delete (this option is nestled where the "New Email" button sits typically). This will remove the meeting from your calendar. If you need to do it for all other members as well, send a "reply all" on the invite with these instructions prior to deleting the meeting series.
2.Get permission to cancel meetings in all user mailboxes using the cmdlet:
Remove-CalendarEvents -Identity <mailbox email address> -CancelOrganizedMeetings -QueryWindowInDays 120
Since there is no way to change the organizer of the meeting, which can all be a great deal of work, you can refer to:
https://learn.microsoft.com/en-us/answers/questions/298859/howto-manage-calendars-when-employee-leave-the-org.html
If an Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.