C.R.S. § 24-51-1207

(1) Upon thirty days’ written notice to the association, any person enrolled in the health care program may cancel enrollment for himself, and any retiree may cancel enrollment in the health care program for his dependents. (2) Enrollment may be canceled by the association upon thirty days’ written notice to any person enrolled in the health care program whose premium amount has not been received by the first day of the month for which coverage was being purchased.