How to prevent the Remote Desktop client from retaining the previous user/otp name
In a user's "Documents" folder there is a hidden file called "Default.rdp", which is used to store default preferences.
If you open this in a notepad and add the value:
Then that user's RDP client will no longer save credentials.
Sometimes previously saved values will still be used by the popup credential tile (which we consider to be a bug). To clear that out, find the affected server key(s) under regedit at
HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers
and delete their UsernameHint. (You can just delete the whole key if you want, though it will forget its RDP certificate fingerprints, if any, and make the user re-agree to the "do you want to trust this server" popups).
You can also perform the "public mode" behavior in a one-off fashion by launching mstsc.exe with the argument "/public"