How do I cancel a meeting invite sent by another user for everyone

Hi Nikky_14, 

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Sting-Ng - Microsoft Community Support Specialist

Dear Nikky_14,

Good day! Thank you for posting to Microsoft Community. We are happy to help you.

Based on your description, if your organization uses both the Outlook client and the Teams client with the same account internally, you can cancel the recurring meeting in the calendar of the user who has left the outlook by using the following methods, restart the outlook client and the Teams client after that, and then wait for the calendar to synchronize.

• First, I want to confirm whether the user is still licensed for Office 365 Exchange Online. If so, please kindly ask your admin within your organization for help to use the Office 365 admin account to add the Full Access and Send As permissions from the user's mailbox to the admin account. You can get more details with this official document: Accessing other people's mailboxes in Microsoft 365
• Unfortunately, so far the organizer of teams meetings cannot be changed, but if you configure the administrator account in the Outlook client with the above, the user's mailbox will automatically appear under the management mailbox. Just go to the user's mailbox's calendar and find the meeting to cancel it, see this article on how to cancel the meeting: Cancel all future meetings in a series (And all invited users need to delete the meeting themselves in the same way.)
• If the user's license has been removed, in Office 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 mailboxand 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.

If you only use Teams internally, then sorry you're not the meeting organizer, you can't edit the meeting details, so to remove all future meetings in the series from your calendar, you'll need to refer to: Cancel all future meetings in a series

These steps will also remove from the calendar any meeting series that have appeared in the past. If you are not the meeting organizer, the only way to delete future events without deleting past events is to delete each instance of a recurring meeting individually. Microsoft is currently working on a way to delegate the organizer role to more people so that can be fix that issue when a organizer leaves the company, you can follow on status on the feedback portal: Allow Delegation of MS Teams meeting

Your patience and cooperation will be highly appreciated. Hope you all the best!

I appreciate it. Thank you for your support 

Sting-NG - Microsoft Community Support Specialist