Michigan Compiled Laws, Chapter 700. Estates and Protected Individuals Code § 700.5217

Sec. 5217. A guardian's authority and responsibility terminate upon the guardian's death, resignation, or removal or upon the minor's death, adoption, marriage, or attainment of majority. However, a termination does not affect the guardian's liability for prior acts or the obligation to account for the ward's money and property. The guardian's resignation does not terminate the guardianship until it is approved by the court. A parental appointment under an unprobated or informally probated will terminates if the will is later denied probate in a formal proceeding.