The Department of Correctional Services shall fulfill those functions of state government relating to the custody, study, care, discipline, training, and treatment of persons in correctional and detention institutions. There shall be separate divisions within the department to assist in fulfilling these functions. The divisions shall be the Division of Community-Centered Services, the Division of Administrative Services, and the Division of Adult Services. The Director of Correctional Services shall appoint an assistant director as head of each division and may remove or change the powers and responsibilities of the assistant director of any of the divisions at his or her discretion.