In tip 2118, we unset Use Personalized Menus manually.
To do it via the registry, navigate to:
Changing the String value of IntelliMenus from Yes to No turns off the option, and visa-versa.
If the user is currently logged on, they would need to logoff/logon to activate the change. If they happen to manually go to the Start Menu Properties screen, they would notice that the check box has already been set, just pressing OK would activate it.
If you make the change in a logon script, it will activate immediately.