I need to no how to remove my name from two birth certificates as I've just found out that I'm not the biological father

You cannot change a legal document without a valid court order.

MRS.S

Contact your local Dept.of Vital records and they will give you the information that your County/State requires.

You need to give us more details here. Even if you are not the bio father, depending on the circumstances, you may still be the legal father because of being on the birth certificate.

We need to know your relationship with the mother, what state (region) you live in, how old are the kids, etc.