If the other user is no member of the administrators group he wont have administrative capabilities.
As example he will access te user account panel and change his own account but no anothers ones. He can access to the registriy but he cannot change any system configuration. Only its user settings.
So you should worry about it and its capabilities, he wont can change the system settings. If you as example block regedit.exe he can make the exactly same changes using another tools.
If you still want to do it can change the assigments rights of that users using the local policy editor (gpedit.msc) and the ACLs of the executable you want to change.
If you see that the user is capable for change System Settings check its group membership.