The best is to catch them on the job. Their hormones are stronger than their survival instinct. Another advantage of this method is that you will be so pissed off with his dastardly actions that it will be much easier to remove the boy's head, without feeling like you're murdering your pet.
Discussion
I don't want to eat him 😱
I just need to clip one wing so he will stop flying over my chicken proof fence I to the veggie garden
He will spawn roosters that you'll need to put in the pot.
They say one shouldn't name one's roosters, but I give them names like Casserole, Soup, Coq-au-vin, Broth(er), etc. I find this helps maintain decorum in the flock.