You do want to solve for peace in the flock. Flocks are not stagnant and are really constantly changing. Animal husbandry is making decisions for the flock, not individual birds.
So how is the flock with the rooster with this hen pulled out. Are they happy with him? If so, I would be tempted to keep that flock and either just keep this bird separated. With a hard molt, the hormones can really dive. What does her comb look like? If it is pale and almost grey, her hormones have dived, and that has a lot to do with pecking order. It may be that when she gets over the molt, she will be fine. But it also might be that she just does not fit with this flock.
However, if the cockerel picks a new victim, he is the problem. He should then be culled. If he is an asset to the flock without her, I would not be too quick to cull him for her. And I would definitely try separating him, and adding her to see the flocks reaction before making a decision.
My point is - be sure and look at the whole flocks behavior. It could be that you remove the cockerel, and she still won't be accepted in the flock.
Mrs K