That is dependent on your state laws. See link below on the laws in your state.
First contact child support enforce on their procedures for modifying or discontinuing support. Take a woman with you to actually ask the question as sometimes they are less accommodating of men. If they have no procedure, you will need to file a motion to modify support with the court. This is similar to a normal modification of support, except you are asking to have support stopped. This can be done Pro Se.
See links below.
Child support payments change or stop only by order of the venue that issued the order for support.
How do I stop the payments now?
You can stop child support payments on the grounds that the child is not your biological child only if you did not know that when you agreed to the support, and if a Court approves your request to stop.
You send in your child support payments regularly and on time.
Keep current on your child support payments and make sure the courts are recording payments correctly.
If you relinquish your parental rights, you are still not going to get child support payments. The child support is for the child.
Child support payments usually stop at age 18, unless some payments have been missed along the way ... Providing ALL your payments for child support are fully up to date and paid in full, you can file in court to have these stopped.
In most cases, a mother cannot legally stop child support payments without a court order. Child support is typically mandated by a court and must be paid until the court modifies or terminates the order.
Your spouse has no authority to over-ride a court ordered child support.
Whatever you do, do not stop paying child support. You have to get the current order modified by a judge to be able to stop the payments.
Generally, yes, the child is still his child. The support payments would likely stop if the new husband adopts the child, but he can't do that unless you agree to it.
No. Alimony is intended to support the ex-spouse (generally, for a limited period of time). Child support is intended to support the children.