Each commissioner and the president of the board of city commissioners shall hold office for four years commencing on the first day of July of the year in which the officer was elected and until a successor has been duly elected and qualified. The commission shall establish by ordinance a procedure whereby one-half of all commissioners, as nearly as practicable, are elected biennially. The president or any other member of the board may resign from office by filing a written resignation with the city auditor, who shall submit the resignation to the board of city commissioners at its next regular meeting or at a special meeting called for consideration of the resignation. The resignation is effective upon its acceptance by the board.