A girl I met after a one night stand got pregnant and wants to have the baby knowing I am unprepared for it.
She wants to sign a declaration/contract/clause to absolve me from any future financial and parental responsibilities.She says she will treat me as a sperm donor.
Where can we go to have this done?

I don't think its as easy as signing a "contract". Go talk to a family lawyer to see what advice he/she can give you.

You will need a family law attorney to draw up contracts to relieve you of your parental responsibility. Now, understand that unless the child is adopted, you may continue to be financially responsible, especially if this girl uses AFDC or Medicaid. You chose to lie down and have unprotected sex, she is going to have to bear the brunt of the responsibility of raising a child, what makes you think you are so special not to have to share in that responsibility?

This really sickens me that men think that they do not have to share in the responsibility of raising children. If this baby is yours, and I would DEMAND a paternity test, you are 1/2 responsible too.