What you are really asking about is terminating a parent's right here and generally speaking, that is not an easy task.  I am assuming that there is something here in the facts that may help you in the direction you seek only because he has supervised visitation.  That would mean that the court thought that he could not have the children on his own and that this was "in the best interest of the children,"  the standard used.  If you terminate his rights it terminates support as well.  I think that you should speak with an attorney in your area on the matter.  More facts are needed.  Good luck.