Whenever a Commissioner determines that a building or other structure assigned to a bureau under his control must be removed, he may authorize the Purchasing Agent to sell such building or other structure for removal by the purchaser.  The Purchasing Agent shall use the method of sale which he finds most in the public interest.  The Purchasing Agent shall specify terms and conditions of sale, except that such terms shall not include credit, and he shall fix the amount of bond or cash deposit to be given by the purchaser to guarantee removal of the building or structure and clearance of debris from the premises.