I've got 6 Red Ranger cockerels that are practicing being roos right now. One of them tried to face me down about a week ago and savagely pecked me on the arm hard enough to leave a bruise and tried to kick me (thankfully missed or I would have been bleeding too).
I grabbed him by the neck feathers, scruffed and pulled on him like a dominant roo would, and he was greatly surprised but suddenly realized I actually was 20x bigger than he was and WILL win by default. He hasn't tried it since (and he honestly is a very nice boy, he's just being a teen rooster! Hormones suck. *L*).
I don't hesitate in getting physical back with the roosters. Scruff them, pick them up and hang them upside down, chase them away from the hens, shove them around with my boot if they're getting shirty with me...I've even heard of people dunking them in rain barrels quickly and then letting them go.
Now, I know some folks may be horrifed by me suggesting this because it sounds like abuse...and I want to reassure that I would never treat any animal like this without a very good reason. Protecting my body and the bodies of other people, especially children, who visit my chickens is essential and non-negotiable as far as good reasons and should be for every rooster owner. My chickens are all loving, lazy lap birds who've been gently snuggled and petted since they day they came home...But I want to stress that roosters understand one thing in life: Might. They compete with each other in physical contests of strength for dominance. This is their instincts and their culture and it's important to understand that.
Getting physical back with roosters works. A lot of folks here have been able to keep their roos and have them go on to be great flock guardians and family members with these techniques. The point is not to HURT them beyond maybe what it feels like getting their feathers tweaked. Mostly you're just reminding them that you ARE much bigger, you ARE in charge, and they will never win a fight against you.
If they are still too dumb/mean after working with them for a bit, then you've likely got a serious problem that you don't want to be passing onto chicks. There are too many perfectly sweet, loving, and balanced roos in the world to bother with overly aggressive ones. Cull and enjoy a nice dinner.