As an adult is there any way to get your parents names off your birth certificate? Can that area of the birth certificate be blank?

No.

No, we get to pick our friends, but family we are stuck with

I have heard of adult adoption. Is this one way to change that?

No, an adoption is an addendum to a birth certificate. It doesn't replace it in the county records. However, the adoption record can be used in place of the birth certificate wherever a birth certificate is required.

As an adult is there any way to get your parents names off your birth certificate? Can that area of the birth certificate be blank? depends on the state

Maybe just call your state office where these records are kept?