Same problem here, both on Linux and Windows. As a consultant you are often obliged to work with yet-another-account. With MS products this is very annoying.
If you just want to switch accounts: Quit teams (and save the old configuration in a tar or zip if you want to keep it for later use), remove the configuration folder and you will be asked to enter an account and the login credentials next time you start Teams.
You can login as guest but sometimes you want to switch between accounts. Just use above method to create several zip or tar archives. Quit teams (do not only close the window, go to the taskbar and quit the application), extract the correct archive and start Teams. Perhaps you should refresh the archives from times to times. If all fails you can always start with an empty configuration.
Linux: The configuration can be found in .config or in ~/snap/teams-for-linux - in my installation the files inside the snap configuration are hidden ("ls -a")
And for those that have to deal with more than one Outlook account: Firefox and the Firefox Multi-account Containers allow to have several different Outlook mailboxes open at the same time. Only downside is that you still cannot merge Outlook calendars. Worked previously with davmail :-(