I got with child an the guy I was with I thought was my son father but .When we got the test he was not the father I was trying to change his hole name because the guy had wanted his name back when he found out that my son was not his child.

You need to try to find the legal father and seek permission if possible.

Where? You have to file a legal name change if that is what you are asking.

That involves an Attorney and the Courts.