The bird is probably being picked by pen mates.  There are "anti-pick" salves available at the feed store that will help healing but mostly they taste bad so other chickens will stop (slow down) the picking.  Beak trimming (remove about 1/4 of the upper beak) of all the birds will work as well however, loss of production may occur and the beaks will grow back and picking will resume.  Removing the bird from the group will work, but re-introducing the bird back later will be difficult, fighting with generally result.  Feather picking is hard to fix, persistence will help.