The ordinance provided for combining said offices shall provide the date when the combination shall become effective, which date shall not be less than three months from the date when the ordinance becomes effective; and on and after said date the office of treasurer or clerk, as the case may be, shall be abolished. Any city which as herein provided, combined the office of treasurer with that of clerk or the office of clerk with that of treasurer may terminate such combination by ordinance, fixing the time when the combination shall cease and thereafter the duties of the offices shall be performed by separate officials: PROVIDED, That if the office of treasurer was combined with that of clerk, or an elective office of clerk was combined with the office of treasurer, the mayor shall appoint a treasurer and clerk who shall serve until the next regular municipal general election when a treasurer and clerk shall be elected for the term as provided by law unless such city has enacted an ordinance in accordance with *RCW
35.24.020.