To clear the cache for New TeamsMicrosoft Teams:
Click ‘Quit’ on Microsoft Teams (you can do this by right clicking on it in the taskbar).
Go to:
C:\Users\user.name\AppData\Local\Packages\MSTeams_8wekyb3d8bbwe and delete the whole folder
Tip: to find the AppData folder you will need to go to View > Show > Hidden Items
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To clear old Team cache:
C:\Users\user.name\AppData\Microsoft\Teams and delete the whole folder