Every trust shall be revocable by the trustor, unless expressly made irrevocable by the terms of the instrument creating the same. Provided, that any trust may be revoked by the trustor upon the written consent of all living persons having vested or contingent interest therein. The term "contingent interest," as used in this section, shall include an interest which a beneficiary may take by purchase, and exclude any interest which a beneficiary may take by descent. Provided further that this section shall not apply to a spendthrift trust unless same is created by the trustor for his own benefit.
Laws 1941, p. 263, § 41.