Change Windows password when in multiple RDP
Open "On screen keyboard" (osk.exe)
Send Ctrl + Alt + Del by mouse-clicking each on key individually, in the most nested RDP session.
If that does not work try holding Ctrl+Alt on your keyboard and clicking Del in OSK in the the RDP session
You can always open a "CMD" command prompt on the VM and reset the password via command line.
When you get the C:\ prompt, you would type something like "net user administrator Ch@rli3" and that would change the administrator account's password to "Ch@rli3".
If you have a nested RDP session and the on-screen keyboard is disabled, you can try opening up PowerShell and running the following command:
(New-Object -COM Shell.Application).WindowsSecurity()
Then enter in your existing password, new password, and hit enter.