If you are not hatching eggs, and have small children who want the chickens as pets, why keep any rooster. It likely is just not worth the risk.
At the very least, get rid of the RIR. They are known to be more aggressive as roosters. Cochins are known to be gentler even as roosters.
1 rooster for 9 hens is very adequate. Your RIR should be kept from the hens. He should not be forcing nonlaying hens to mate. His hormones are running wild. Blood drawn is not acceptable.
If you really, really want a rooster around your place, pick the sweetest Cochin and rehome the other 2. Watch that Cochin to be sure he is not taking over now that the others have left in a way that is overly aggressive.
Roosters can do a lot of damage to small children very quickly. Their faces are close to the ground and can receive injury to the eyes from the rooster spurring and clawing. It is simply not worth keeping roosters unless you want the responsibility of training and supervising both kids and roo.
My thoughts.
Lofmc