Any certificate of membership, or policy, issued by such a mutual insurance corporation may be canceled by the corporation by giving thirty days' written notice thereof to the insured; or such cancellation may be upon demand of the insured; and such cancellation, when so made, either by the corporation or by the insured, shall be upon a pro rata basis, and the cancellation of such certificate or policy shall release the member from all other future obligations to such corporation.
Iowa Code § 519.8