I've disabled login user name change.
After deleted the user account (local user account with admin permission), I'm not able to log in windows.
Shift-restart, start troubleshoot, command prompt.
Create the same user account with same password and add to admin group.
But after restart, still not able to log in. If open troubleshoot command prompt again, run command 'net user', can't see new created user account. Seems all changes made in troubleshoot command prompt are lost.
If select to boot safe mode, because I've set administrator need to set new password on next login, can't directly log in administrator account.
Set new password, it will print "Access is denied".
Not sure if this can be fixed.