Legal Question in Family Law in Oregon

NO, adoption is a permanent legal act. You cannot be unadopted.

ORS 109.041(1)(b) says that once the adoption has been finalized, the legal relationship of the child to his or her birth parents is the same "as if the adopted person had been born in lawful wedlock to the adoptive parents and had not been born to the natural parents."

No going back. But you could go forward, meaning that you could be adopted (again) by somebody else (including the parents from whom you were adopted to begin with).