Mich. Comp. Laws § 168.256

Sec. 256. After the filing of nominating petitions or filing fee by or in behalf of a proposed candidate for the office of county road commissioner, such candidate shall not be permitted to withdraw unless a written notice of withdrawal is served on the county clerk or his duly authorized agent not later than 4 o'clock, eastern standard time, in the afternoon of the third day after the last day for filing such petition, as in this act provided.