if for some reason you HAVE to give a user root privileges you can follow these steps i will give you on this post. but be sure to use this very carefully and you trust the user you are giving admin right because they can do a lot of damage to a server if you set this settings because they can be abuse.

Intruders usually create a user account with the ID number set to
zero. A user account with a user ID of zero has root privileges. so all you have to do is edit a user's account and set their UID to 0

0 = root