You need to think like a chicken.
1. In the chicken world, the alpha rooster gets the highest perch. Don't let him roost above your head height, and NEVER let him on your shoulder.
2. In the chicken world, the subordinate hens groom the alpha rooster. Don't pet and cuddle your rooster, that is telling him directly that he's the boss.
3. In the chicken world, the subordinate roosters don't mate the alpha's hens while the alpha can see them. If you see him mounting a hen, go kick him off. You don't need to be nasty about it, but put a toe under the tail feathers and gently kick him off every time until he stops. Those are YOUR hens, not his.
4. In the chicken world, if the subordinate rooster puts a feather out of line, they get disciplined. Have you ever seen a rooster discipline a hen? He'll squawk and chase her all over the place and peck her on the head. So if he does anything aggressive towards you, like sneaking up behind you or coming towards you with his head low and his neck feathers fluffed up, think chicken! Squawk and stomp your feet and flap your arms and chase him all over the place. If you can catch him, either hold him down in the dirt until he stops struggling, or pick him up and carry him upside down until he stops struggling.
I usually do this while telling him something along the lines of "Do you really want to get into this with me, Buster? Because I OWN your little fluffy butt, and I can do this all day long. I'm the biggest, baddest chicken you've ever seen and we can be friends, or I will be your worst nightmare. See that killing cone over there? You could go from the coop to the crock pot in five minutes, Buddy."
5. Don't keep an aggressive rooster. With any young rooster, they may try to dominate you once, and that's OK as long as he learns his lesson after you chase him around. But some roosters simply are very aggressive and don't learn, and they can be very dangerous animals. We have a Two Strikes and You're Dinner policy around here. Once, I'll chase you around and see if you learn, twice, and you're history by nightfall.
There are thousands upon thousands of very sweet, non-aggressive roosters in the world, and many of them are culled every day simply because the people can't keep them all. So if this bird turns out to be aggressive, you can probably try again with another rooster for free, as long as you're not looking for a show quality bird. For example, I only breed from non-aggressive roosters because aggression is partly genetic, and I don't want to breed aggression into my flock. But that means that half of every hatch are lovely young cockerels. I will put them on Craigslist for a week, but if no one wants them, they are culled. I am always thrilled when someone wants one of my boys for a flock rooster instead of their being killed, and I know many, many other people feel the same way.
Hope that's helpful! One last piece of advice--in the future, don't make friends with your rooster. Mostly ignore them. Make friends with your hens if you wish, but treat your rooster like the potentially dangerous animal he is.