At this stage, he's learning to take over his job as protector of the flock. He's training the girls to pay attention to his commands, and get behind him, so he can protect them. There are no real predators, so you are filling that role. While it's good he's doing this, and the girls are learning, it's not good that you are the substitute predator. When mine get to this stage, I do allow the cockerel(s) to herd the girls, and stand between us for a couple minutes, then I usually will move him out of the way. I have actually picked them up, and put the cockerel(s) separate for a few minutes, while I enjoy the company of the pullets, without the cockerel(s) interfering. This helps keep the females from seeing you as a threat, no matter what the cockerel is trying to tell them, and by moving the cockerel out of the way, it sends the message that you are in charge, not to be confused with being a threat. Rooster training begins early, and gently.