Zusätzliche Anmelde- oder kontobezogene Probleme innerhalb von Microsoft Teams for Business
Thank you for your response, Peter. Have you tried to remove your personal account on the device itself?
Here's how:
Select Start button > Settings gear icon > Accounts icon > Email & accounts.
Choose the account that you want to remove from the device.
Select Remove and then follow the instructions.
After removing the account completely, restart your device. Then check to see if you can sign in to the right account.