The hearing examiner shall be appointed by the mayor, subject to confirmation by the city council. An examiner may be removed from office at will and without cause by the mayor; however, such removal shall not affect the ability of the examiner to complete any cases for which he or she has already undertaken the hearing. The examiner may be retained under a professional services contract for a specified term on conditions determined by the mayor and approved by the city council. The contract may also provide for examiners pro tem to serve in the absence of the examiner.