Hi Matt,
The instructions to delete a teams free account are here: https://support.microsoft.com/office/2c28cfcf-3...
To delete the account from your desktop,
Open registry editor, go to Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Teams and delete the keys for homeuserupn and webaccountid.
In the teams app in Windows, delete folders in %AppData%\Microsoft\Teams\ to clear the cache -
Right click on the teams icon and choose Quit
Then delete or rename the following folders:
%AppData%\Microsoft\teams\application cache\cache
%AppData%\Microsoft\teams\blob_storage
%AppData%\Microsoft\teams\databases
%AppData%\Microsoft\teams\cache
%AppData%\Microsoft\teams\gpucache
%AppData%\Microsoft\Teams\IndexedDB
%AppData%\Microsoft\teams\Local Storage
%AppData%\Microsoft\teams\tmp