Why do you want a rooster? The only reason you need a rooster is if you want fertile eggs. Everything else is just personal preference. I always recommend people keep as few roosters as they can and still meet their goals. In your case, that may mean no roosters. But that is your decision.
There is a lot I don’t know about your situation, age, how much room they have, how you manage them, and many more things. In general, that behavior is not normal. It is normal for them to work out a pecking order and flock dominance when they are adolescents growing up in the flock, but if one is causing bleeding you have a dangerous situation. Chickens can be attracted to blood. They could easily kill another chickens pecking at the blood or wind up eating it alive.
I strongly suggest you keep that one cockerel away from the flock so he can’t cause damage like that. Whether you isolate him, get rid of him, or eat him is your choice, but your pullets are in danger with him behaving this way.
