(a) by the extinction of the trust;

(b) by the completion of his duties under the trust;

(c) by such means as may be prescribed by the instrument of trust;

(d) by appointment under this Act of a new trustee in his place;

(e) by consent of himself and the beneficiary, or, where there are more beneficiaries than one, all the beneficiaries being competent to contract, or

(f) by the Court to which a petition for his discharge is presented under this Act.