70 ILCS 1863/23
Members of the Board shall hold office until their respective successors have been appointed and qualified. Any member may resign from his or her office to take effect when his or her successor has been appointed and has qualified. The Governor and each County Board Chair may remove any member of the Board they have appointed in case of incompetency, neglect of duty, or malfeasance in office. They shall give such member a copy of the charges against him or her and an opportunity to be publicly heard in person or by counsel in his or her own defense upon not less than 10 days' notice. In case of failure to qualify within the time required, or of abandonment of his or her office, or in case of death, conviction of a felony or removal from office, the office of such member shall become vacant. Each vacancy shall be filled for the unexpired term by appointment in like manner as in case of expiration of the term of a member of the Board.
70 ILCS 1863/23