You'll have to either give him the spawn commands (which is usually reserved for higher tiers of ranks, though mainly for the owner/superadmin rank). There was a way to disable spawn editing for any/all players on the server, but it's been around 3 years since I last was on a server (I had rights equal to that of being superdamin, in other words I was co-owner even though I played the server for about a week, I was extremely helpful on the server).
But because of that gap, I don't remember the command, not to mention that Tshock's commands have changed since then (the input "words" are different from last time).
If you trust your friend with your life, you can make him SuperAdmin, which essentially gives him the exact rights you have, which involves being able to turn off the server from within the game, lower other players' ranks (including your own), and others.
If you do, you can either get a database editor for Tshock and change his rank that way, or change it in game.
The command for it IIRC should be this:
/user group [your friend's IGN here] superadmin
If your buddy's name is Fred, it'd be /user group Fred superadmin
but if your buddy's name is separated by a space, for example the name Bob Joe, you'll put this in:
/user group "Bob Joe" superadmin