How to remove orphan users from teams channels

[HShah18]

Hi, 

I'm a sharepoint online administrator and I have been trying to remove all the orphan users from sharepoint teamsite and MS teams at work, I was able to remove them sharepoint using a third party tool called sharegate, but it couldn't remove the orphan users from Teams private channels. 

Please can anyone suggest what I should do to remove all the orphan users from Teams channels? The error I get is shown below. How can I add my admin account to Private channels and clean the orphan users accounts?

Error Messages

Error while loading items from scope 'https://???????????/': You are not authorized to perform the requested operation.

[#2]

If the users are removed from the Team where the private channels live, they should be removed from the PC as well! Although, I don’t know how ShareGate works in that case cause removing PC users from a SharePoint perspective won’t work. They will be added back! From a Teams perspective you can remove users from the Teams via Teams admin center! If you just need to remove Private channel members from the PC only, you can use the same to remove them from there!

Adam