The trustee may be discharged from his office only as follows:—

   (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.