Illinois Statutes Chapter 755. Estates § 5/11-14.1. Revocation of letters

(a) Upon the minor reaching the age of majority, the letters of office shall be revoked only as to that minor and the guardianship over that minor shall be terminated. The letters of office and the guardianship shall remain as to any other minors included in the same letters of office or guardianship order.

(b) Upon the filing of a petition by a minor's living, adoptive, or adjudicated parent whose parental rights have not been terminated, the court shall discharge the guardian and terminate the guardianship if the parent establishes, by a preponderance of the evidence, that a material change in the circumstances of the minor or the parent has occurred since the entry of the order appointing the guardian; unless the guardian establishes, by clear and convincing evidence, that termination of the guardianship would not be in the best interests of the minor. In determining the minor's best interests, the court shall consider all relevant factors including: