Deleting scheduled events in Exchange Online/Teams

Hi tcboeira,

here are some options you can try:

1. If the user is still licensed for Office 365 Exchange Online, you can use an Office 365 admin account to add Full access and Send As permissions to the user's mailbox. Configure this admin account in the Outlook client to access the user's mailbox and cancel the recurring events.
   
   

2. If the user's license has been removed, in Microsoft 365,  the user's old email, contacts, and calendar are retained for 30 days.So in the 30 days, I suggest you temporarily re-assign the Office 365 license to the user, then convert it to a shared mailbox and remove the license. 

   
   After that you can add the Full access and Send As permission of the shared mailbox to the admin account based on same methods I mentioned above and access the shared mailbox to cancel the meeting.