How do I stop child support against ncp

My child's father lives with me and our son. All three of us live with my mother and are currently under her benefits case, receiving medicaid and food stamps. I am trying to stop my case so he can pay off everything he owes because he has a tremendous amount of arrears. He is known to the court as the non custodial parent, however if I'm not mistaken that means that the child does not live with him. Yet we all live together. Do I have any options regarding this matter?