J.S.
Oh this is a tough one. If he were younger I would say let him quit, and if it were a different sport I would say make him stick it out, but football (I'm assuming you're talking about Pop-Warner or something similar) is a whole different animal. The sport (and that league) requires such a ridiculous commitment of time and is so, so physical and the coaches and culture can be pretty nutty (and I say that as a hockey mom LOL!). I can see how and 11 year old who had no idea what he was in for would want to quit.
If I were you, I would make him stick it out through training season, which, if I recall correctly, lasts about 4 weeks. Let him get to the point when the practices slow down to 2 nights a week and let him taste what it's like to be in a game. He may have more fun when the intense conditioning and training period is over. If he still hates it then, I would let him drop it.