(1) Any party to a guardianship proceeding may request termination of the guardianship by filing a petition and supporting affidavit alleging a substantial change has occurred in the circumstances of the child or the guardian and that the termination is necessary to serve the best interests of the child. The petition and affidavit must be served on the department or supervising agency and all parties to the guardianship.

(2) Except as provided in subsection (3) of this section, the court shall not terminate a guardianship unless it finds, upon the basis of facts that have arisen since the guardianship was established or that were unknown to the court at the time the guardianship was established, that a substantial change has occurred in the circumstances of the child or the guardian and that termination of the guardianship is necessary to serve the best interests of the child. The effect of a guardian's duties while serving in the military potentially impacting guardianship functions shall not, by itself, be a substantial change of circumstances justifying termination of a guardianship.

(3) The court may terminate a guardianship on the agreement of the guardian, the child, if the child is age twelve years or older, and a parent seeking to regain custody of the child if the court finds by a preponderance of the evidence and on the basis of facts that have arisen since the guardianship was established that:

(a) The parent has successfully corrected the parenting deficiencies identified by the court in the dependency action, and the circumstances of the parent have changed to such a degree that returning the child to the custody of the parent no longer creates a risk of harm to the child's health, welfare, and safety;

(b) The child, if age twelve years or older, agrees to termination of the guardianship and the return of custody to the parent; and

(c) Termination of the guardianship and return of custody of the child to the parent is in the child's best interests.

(4) Upon the entry of an order terminating a guardianship, the court shall enter an order:

(a) Granting the child's parent with legal and physical custody of the child;

(b) Granting a substitute guardian with legal and physical custody of the child; or

(c) Directing the child to be temporarily placed in the custody of the department for placement with a relative or other suitable person as defined in RCW 13.34.130(1)(b), if available, or in an appropriate licensed out-of-home placement, and directing that the department file a dependency petition on behalf of the child.