Mo. Rev. Stat. § 87.240
If a member ceases to be a fireman except by death or retirement, he shall be paid on demand the amount of his accumulated contributions standing to the credit of his individual account in the members' savings fund, and such a member who has left his contributions with the system may later withdraw his accumulated contributions at any time prior to the beginning of his retirement benefits.
(L. 1943 p. 708 § 6, A.L. 1959 S.B. 314 § 86.550)