Hi,
Are the chicks weaned yet? If so, this is the problem. Weaned chicks must be separated from the parents and the nest box should be removed as soon as the chicks leave the box. The female and usually the male do not want the weaned chicks to stay. In the wild, this is nature’s way of preventing related birds from breeding. If the hen continues to pluck the male, then separate them for now and let her calm down. If the chicks are still being fed, then you may need to remove them and try feeding them, since the hen is drawing blood. You can try removing the hen, to see if the male would feed the chicks. She might calm down if she is separated for a short time. But since she is drawing blood, you need to remove the chicks before she ends up killing them.
Thank you for asking Lafeber,
Brenda