Except as otherwise provided by this charter, the head of each department shall be a director, appointed by the mayor, and shall serve at the mayor's pleasure. Each director shall administer his or her department in accordance with this charter, the applicable ordinances adopted by council, the rules and regulations made by the mayor, and general law, except as general law may be limited by council. Each director may, subject to applicable civil service regulations, appoint, promote, transfer, reduce or remove division heads, officers and employees within his or her department.