I want to punish AFK(Away From Keyboard) player.
So, I use http request save the steamid in my server
but how could I use this id to kick this player when
he add other people create custom map?
you can't prevent people from starting the map , you can only prevent them to play it by kicking them off right at the begin
And you probably shouldn't do that, since it would cause unnecessary grief to the other players (4v5 and wasted time etc). At the moment it's probably best to just leave that in the hands of the lobby system, and hope that valve improves upon it someday.
Might even go against some usage agreements to give penalties to players outside game modes.