(a) Except as provided in subdivision (b), if all beneficiaries of an irrevocable trust consent, they may compel modification or termination of the trust upon petition to the court.
(b) If the continuance of the trust is necessary to carry out a material purpose of the trust, the trust cannot be modified or terminated unless the court, in its discretion, determines that the reason for doing so under the circumstances outweighs the interest in accomplishing a material purpose of the trust. Under this section the court does not have discretion to permit termination of a trust that is subject to a valid restraint on transfer of the beneficiary’s interest as provided in Chapter 2 (commencing with Section 15300).