Roosters are naturally aggressive. They have two purposes in life: first is to protect their flock and second is to help them find food.
You can train a rooster to be tame, yet it will not close the fact that he can still be aggressive to other people.
This is understandable because they are prey animals. Meaning, they are vulnerable to threats. As a prey, rooster is suspicious to sudden changes in surroundings. To secure his territory, he will defend it to the extent that he will sacrifice his own life.
Increase of testosterone when they reach puberty after four months causes roosters to be aggressive. They will then exhibit strength with chest bumping and showing manly behaviors.
Resorting to violence like intimidating, kicking and shaming roosters to gain dominance will just give them more reasons to be violent and protect their flocks.
If you don’t want an aggressive rooster in the backyard, you should find him a new home or a large property where his protective nature will be an asset to the flock.