I am wanting to help my fiancŽ he pays his child support doesn't see the child and the mother is always harassing him about money. He is not on the birth certificate and the child doesn't carry his last name. He wants to sign over what rights he has to get her out of his life can he do it?

Normally no, unless the child is going to be adopted by the child's step-father. Read this (https://www.askmehelpdesk.com/family-law/signing-over-rights-read-first-116098.html).

A few things aren't clear. Is there a child support order requiring him to pay child support? Has be filed for visitation rights?