If your name is on the birth certificate because:
…someone told the hospital that you were married to the mother but you were not actually married to the mother. Call the Division of Child Support at 1-800-457-6202 and tell them you want to do a "paternity establishment action."
...you were married to the mother. You are legally presumed to be the father until you get divorced and your divorce addresses paternity of the child in question or you file a "disestablishment action" Our office does not handle either type of court action. Since there are time limits on when you can seek to disestablish paternity, you should consult with an attorney.
. . . you signed a paternity affidavit. You must act within certain legal time limits if you want to undo a paternity affidavit. Our office does not handle rescissions or challenges to paternity affidavits. You should consult with an attorney as soon as possible or if you want to try and look into it on your own, the legal time limits are in the statute called the Uniform Parentage Act, Chapter 26.26 RCW.
...a Court order established you as the father of a child. You have to bring a court action to "vacate" the court order. If our office was involved in the court order establishing you as the father we can review the case to figure out what, if anything, our office can do. Call our office at 360-385-9359 to discuss further.