How can i change my newborns birth certificate so i can be listed as the father?

I have a newborn who is 20 days old. My girlfriends ex thought he was the father and signed for it. We did a DNA test and it ended up i was the father. He is willing to admit hes not the father in court if it gets that far. But i read somewhere you have 45 days to change anything on the birth certificate without any paper work or a judge. So i was wondering if changing the father under that qualifys.

I live in California if that helps .How can i change my newborns birth certificate so i can be listed as the father?
Go to court, cos if you don't she can - legally make the other guy pay child support!! BUt, how did you get the DNA test done so quickly!? If you still want to be responsible for this child, Better rush down to the Court house and find out!
I think you should resolve your problem through online resources as there are many online agencies those are providing their services related birth certificate issues in a very easy and cheap way.These agencies are providing their services even at your home step.I can suggest you one of these agencies,so try here.I hope you will resolve your problem.good luck.How can i change my newborns birth certificate so i can be listed as the father?
Go to California's Department of Public Health website that I have included below. They have all the instructions for correcting a birth certificate.How can i change my newborns birth certificate so i can be listed as the father?
hmm a court or like city hall like if u live in sd in downtown just big building and there's many offices for anything and everything