Couldn't you just stay at 1 thread ...
Users & Groups - Search For Users -- Find him/her ... and "Edit Profile & Settings" ... and change his/her Primary Usergroup to Administrator.
Go to the User's Profile and click 'Edit this user in Admin CP' --> Change 'Primary User Group' to 'Administrators'
You'll want to set what the user is able to do in regard to the Admin CP too:
Admin CP --> Users and Groups --> Admin Permissions --> *Select user's name and click 'Edit'*
Also, when you make a thread, please make the subject descriptive of what you are asking? "How can I" or "How do I" doesn't tell us anything. Thanks