Hi @Ant
Do you mean you want to delete the login history in Teams login page?
If so, you could try to follow these steps to clear your client cache file to see if it works for you:
1.Fully close Microsoft Teams.
a.Right click the Microsoft Teams icon in your dock, then click Quit.
2.Open Finder, then click Go and select Go to Folder…
3.Copy and paste the following into the Go to Folder box, then click Go
~/Library/Application Support/Microsoft
4.Right click the Teams folder, then click Move to Trash
5.Relaunch Microsoft Teams.
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