At the moment, Microsoft does not have a way to clear the local cache from within the graphical user interface (GUI), although it has been requested so we won't see this until Microsoft pushes out an update with this feature included. Thankfully, there is a workaround.  Note, this workaround of cache deletion will NOT remove the Microsoft Teams app from your PC.

Here’s the workaround to clear all of the cache from Microsoft Teams:

1. Quit Microsoft Teams by looking in the system tray near the Time/Date field and Right-click the icon and select Quit.
2. Cut and paste the following location into File Explorer: %appdata%\Microsoft\Teams
3. Delete contents of the entire folder.
4. Restart Microsoft Teams.

The files/folders that you deleted will remove everything cached from Microsoft Teams on your Windows 10 PC.  Your new Microsoft Teams cache directory will be restored automatically by using your organization’s Microsoft 365 cloud account. Your previous saved Microsoft Teams settings will be completely erased.

The cache deletion will remove the following Microsoft Teams items from your Windows 10 PC; the web client cache, icons, thumbnails, local message history, your Microsoft Teams display images, and any other Microsoft Teams add-ons. You may need to log back in to Teams again once the app restarts, but you should be able to use Microsoft Teams without any issues.

This method works similarly on a Mac by deleting the following directory; ~/Library/Application Support/Microsoft/Teams. On Windows 10, this cache deletion method is particularly helpful if you are having issues logging into Microsoft Teams if you have multiple accounts, or are trying to remove old Microsoft Teams account information.

So, if you run into any random login issues with Microsoft Teams or the app seems to be running slowly on your Windows 10 PC, this method is the best way to clear all of your Microsoft Teams cache and start fresh.