(a) A trust terminates when any of the following occurs:
(1) The term of the trust expires.
(2) The trust purpose is fulfilled.
(3) The trust purpose becomes unlawful.
(4) The trust purpose becomes impossible to fulfill.
(5) The trust is revoked.
(b) On termination of the trust, the trustee continues to have the powers reasonably necessary under the circumstances to wind up the affairs of the trust.