The parental rights of the parents of a ward may be terminated as provided in this section and ORS 419B.502 to 419B.524, only upon a petition filed by the state or the ward for the purpose of freeing the ward for adoption if the court finds it is in the best interest of the ward. If an Indian child is involved, the termination of parental rights must be in compliance with the Indian Child Welfare Act. [FN1] The rights of one parent may be terminated without affecting the rights of the other parent.