Oh my, are they from a hatchery? The reason I am asking is because my cousin had purchased some from a hatchery and they where doing the same thing. The roosters were especially nasty, she sold all but one hen, and that solved her problem. You can get SLW that don't do that. You should cull them.
Before you do that, what is your protein level? If they pick on the weakest link and draw blood, they will kill. Just a thought.
My rooster is (was til spring started) a very sweet rooster. He would let my son carry him around. Now he sometimes goes after the feed bag when I feed them. I feed them Albright's feed mill 16% protein layer mash. They pick everyones tail feathers out. They have always done that. I got them from Country Junction. The lady that helped me didn't know anything about chickens except chicken parmesian. She worked in the furniture department and they made her catch the chickens. They were fine with Pebbles until she went broody and only came out to eat and drink. I have some slw eggs under my silkie, I don't know if I will replace my girls with the new chicks or get barred rocks. Sigh They are my first chickens we got aand are a mean chick gang, no other way to describe them. I just thought that was partmof the pecking order.