Steps to resolve - Launch MS Word to test and login.
Clear out any Microsoft credentials you have in the Credential Manager.
Remove the account in the Work or school account settings.
Try downloading/running the Microsoft Support and Recovery Assistant.
Try completely removing/uninstalling everything to do with Office from your computer.

Delete the AAD identity folder in :

Settings.dat in C:\Users\AppData\Local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Settings\

All the files under the folder C:\Users\AppData\Local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\AC\TokenBroker\Account