Mich. Comp. Laws § 168.434
After the filing of a nominating petition or affidavit of candidacy by or in behalf of a proposed candidate for the office of judge of probate, the proposed candidate is not permitted to withdraw unless he or she serves a written notice of withdrawal on the secretary of state or his or her duly authorized agent. The notice must be served not later than 3 days after the last day for filing nominating petitions if a nominating petition was filed for the proposed candidate, and not later than 3 days after the last day for filing affidavits of candidacy if an affidavit of candidacy was filed for the proposed candidate. If the third day falls on a Saturday, Sunday, or legal holiday, the notice of withdrawal may be served on the secretary of state or his or her duly authorized agent at any time on or before 4 p.m., eastern standard time, on the next secular day.
MCL 168.434