The existing departments, commissions, boards and other branches of the City government are continued, unless changed by the provisions of this Charter or by ordinance of the Council. Except as established by the provisions of this Charter, the Council may change, abolish, combine and rearrange the departments, commissions, boards and other branches of the City government provided for in the administrative code, but an ordinance creating, combining, abolishing or decreasing the powers of any department, commission, board of other branch, shall require a vote of a majority plus one of the members elected to Council.