There shall be in the Department of Finance a Division of Purchases and Supplies. The Commissioner of Purchases and Supplies shall make all purchases for the City in the manner provided by ordinance, and shall, under such regulations as may be provided by ordinance and by direction of the Board of Control, sell all property, real and personal, of the City not needed for public use or that may have become unsuitable for use or that may have been condemned as useless by the director of a department. He shall have charge of such store rooms and warehouses of the City as the Council may by ordinance provide.