I wouldn't breed an aggressive rooster. What you need a rooster who is nice to his girls and respectful of his human caretakers. While I thoroughly understand your desire to avoid killing your rooster, we must make these difficult decisions. I, too, am a wimp when it comes to killing roosters so I give them to people with full disclosure. These people will process them and feed their families. Honestly, I'd rather roosters be part of the food chain then be part of a cock-fighting ring and used as a training bird.
Rehome this rooster and find another who will suit your needs. And don't forget young cockerels will be nice but when the hormones hit they will turn into what nature wanted them to be: Protective breeding machines that will defend their flock. Roosters are not pets. Don't expect them to be pets. It is their nature to be number one in the flock so they can earn breeding rights. Be mindful of what they are and don't give them a chance to attack. I've trained my roosters to roost when I enter the pen. If they don't I chase them around with a 'grabber' or fishing net until they go to the designated spot which can either be a certain roost or a corner. Smart roosters will instantly go to the 'safe' zone. The not so smart youngster may posture at me only to get pushed and bullied until they go to where I want them. The idiot rooster goes to crock-pot therapy.
And never, ever tolerate a rooster who bullies hens, makes them bleed, and won't let them eat.
Here Stan the Man tolerates a beak-lashing from a low ranking hen.
Real Deal Steele submitting to a dominant hen. Note his frayed hackles feathers due to over grooming by the hens. I had to actually remove him and place him with less aggressive hens.
Dapper Dan proved too aggressive for the hens. While he's smart enough for me to train and will roost the instant I enter the coop, I can't tolerate his abusive behavior toward the hens. He will go to the man down the road.