Close Microsoft Teams and Outlook. Right click the Teams icon in the lower right hand corner of the taskbar (it may be in the ^ area) and click Quit.
Press the Windows + R keys together to open Windows Run. Type in or copy and paste the following %appdata%\Microsoft and click OK.
Find the Teams folder, and right click. Select Delete.
Relaunch Microsoft Teams and sign back in.
Close Microsoft Teams and quit out of it. Right click or command click on the Microsoft Teams icon in the dock and select Quit.
Open Finder and click Go from the top menu bar. Select Go to Folder from the dropdown.
Type in or copy and paste the following ~/Library/Application Support/Microsoft and click Go.
Right click the Teams folder and Move to Trash.
Use Spotlight Search (command + space on the keyboard) and type in Keychain to find Keychain Access.
Within Keychain Access, search for Microsoft Teams to find the Microsoft Teams Identities Cache entry. Right click it and delete it.
Relaunch Teams and sign back in.