My husband got custody of what he was told was his son back in December and we have done a DNA test just because his ex wife has cheated on him with all the children and none so far has been his she while he was deployed to Iraq had him put on three of the birth certificates and now since the boy he has custody of is not his my husband wants him to know his father so is willing to let him go back to be with his mother but the mother does not want the boy back and says she will make him pay child support on him if she does take him because his name is on the birth certificate. How do we go about getting his name off the birth certificate and what do we do with the kid?

How very sad. I hope you find someone who is willing to love and care for this child. How old is he now? Maybe you can get a court order for the mother to name all possible fathers, to give you somewhere to start looking.

How said, how long has he raised his son,

1. in some US states, he may not be able to object to paternity, in other states after 2 or 3 years you can not object. In some US states he can always object.

2. But even if he is not the bio father if he has loved and raised a child how can he ever want to let the child go.
The child I adopted is as much mine as any.

He will need an attorney to take this back to family court

I think to get your husband's name off the birth certificate he will have to file a motion in court to disestablish paternity with his DNA test results as proof that he is not the bio father. At that time he should also ask for a court order relieving him of any child support obligations.