Cal. Gov't Code § 34902

(a) If a majority of the votes cast on the proposition is for it, the office of mayor shall thereafter be an elective office, except as provided in subdivision (b). At the next succeeding general municipal election held in the city, one of the offices of city councilperson, to be filled at the election, shall be designated as the office of mayor, to be filled at the election. The person elected at the election as mayor shall hold office from the Tuesday succeeding his or her election, and until his or her successor is elected and qualifies.
In the case of a vacancy in the office of the mayor for any reason, the council shall fill the vacancy by appointment. If the council fails to fill it within 60 days, it shall call an election to fill the vacancy to be held on the next established election date to be held not less than 114 days thereafter. A person appointed or elected to fill a vacancy shall hold office for the unexpired term of the former incumbent.
(b) After an office of elective mayor has been established, the city council may subsequently submit to the electors the question of whether or not to eliminate the elective office of mayor, pursuant to the procedures enumerated in this article, and thereby reestablish the procedure of selection of the mayor by the city council. If a majority of the votes cast on the proposition are in favor of the elimination of the office of elective mayor, the office shall be eliminated on the expiration date of the incumbent’s term, and on the date the procedure of selection of the mayor by the city council shall be reestablished.