In the Authenticator app, open Settings > Autofill settings > Sync account. On the next screen, you can select on Stop sync and remove all autofill data. This will remove passwords and other autofill data from the device. Removing autofill data doesn't affect multi-factor authentication.
For more info - https://learn.microsoft.com/en-us/azure/active-directory/user-help/user-help-auth-app-faq#autofill-with-authenticator