California Code, Probate Code - PROB § 15404

(a) A trust may be modified or terminated by the written consent of the settlor and all beneficiaries without court approval of the modification or termination.

(b) If any beneficiary does not consent to the modification or termination of the trust, the court may modify or partially terminate the trust upon petition to the court by the other beneficiaries, with the consent of the settlor, if the interests of the beneficiaries who do not consent are not substantially impaired.

(c) If the trust provides for the disposition of principal to a class of persons described only as “heirs” or “next of kin” of the settlor, or using other words that describe the class of all persons who would take under the rules of intestacy, the court may limit the class of beneficiaries whose consent is necessary to modify or terminate a trust to the beneficiaries who are reasonably likely to take under the circumstances.