They are bred for strength and stamina, it is not ingrained in their DNA to kill at all costs, that is trained. Just like pit bulls, it's not the animal. There are some aggressive outliers with any breed of chicken, and yes, they usually have to be culled.
@Nashv755 Is the 2 year old, "top dog" rooster you mentioned no longer around? Remember they're full of hormones and pent up frustration right now. Even non-game cockerels will do this. I have probably 20 cockerels in the yard right now, all alpha roosters have passed away in the last two months, as well as my alpha hens, and there's a power vacuum. I have two giant brothers that are EE/Barred Rock mix that do and take what they want, but have no need to go after anyone, because they're the biggest. Most of the other cockerels are fine staying out of the way, but I have one group of 5 Spitzhauben cockerels that are doing this with each other. One has decided that since he can't win with his brothers, my dog is his target. My dog poops bigger than him. The Spitz boys have gotten into a couple of good scuffles, as did my previous 3 alpha roosters, but they eventually worked it all out once the girls started willingly pairing up with them. If it's normal teenage angst, your cockerel should be chasing around the girls relentlessly too, just watch for the other boys to join in the chase, because they all help each other out when it comes to being little crapheads like that.
There are a couple of options:
If there's not a strong enough alpha rooster in his mind in your flock, he wants that job, and he's making sure everyone else knows it and submits, regardless of their seniority or breed. If he has nasty spurs, trim/dull them and monitor his hostile takeover for a few days and see if once he's made the rounds a few times, he settles down. If you have fragile breed roosters, get them out of there for a few days.
You could put him in rooster jail for a few days (a wire dog crate in the run with everyone else able to stand around). I've never had to for more than a few hours, but even my wildtype breeds are closer to jungle fowl than gamefowl in their heritage. Monitor them, if he's fighting with anyone through the bars, decide whether it's just him and he'll either calm down or becomes dinner, or put another one in another jail if there seems to be an instigator you weren't aware of.
If that fails, you may have to separate him from the flock entirely while another rooster becomes alpha. Then you can try to reintegrate him (sneak him in at night) and see if Alpha will give him a place in the group.
Make sure you're asserting yourself as the ultimate Alpha at all times. He should get out of your way when you walk through, don't let him make you move; he should be easy for you to handle (catching is a different story!); watch for him being a creeper and spin and face him if he's more than just curious.
All that said, if he becomes aggressive toward you or another human - send him to be judged by the Queen of Hearts. Even gamefowl breeders cull manfighters without prejudice. You can chose to give him the time to mature and prove that he's not one, or you can make the call to stop the problem at the first sign, just don't ignore the responsibility to dispatch him if you have to.
If you choose to get rid of him, you know who will answer the ad first. If you don't want that to happen, I suggest reaching out to the local humane society or asking at the local feed store for some assistance with finding a suitable home. There are plenty of legitimate, responsible, and respectable gamefowl owners out there that may be interested.
Remember high school? You stepped in like the Principal and the other guy laughed at him. Hormones, teenagers, different species, same song and dance.
I just heard the Spitz boys outside the window causing some trouble for the fine folk of Hazzard County, I'd better go investigate.

(I know they're up to no good when there's constant crowing, then some commotion, then silence, then ducks. The ducks are snitches.)