After adding a user to the local Administrators group… even though the user is in the local group, they still don’t have effective permissions as a desktop Administrator. They have to at least logoff/logon or reboot for the permissions to take effect. I was wondering if there’s a way to do this via command-line in a seamless fashion.
says, you can use:
klist -li 0:0x3e7 purge
However, after I ran that command, it didn’t make any difference; I still had to logoff/logon or reboot for effective permissions to take place.
Source: Windows Questions