Mo. Rev. Stat. § 78.260
The holder of any elective office may be removed at any time by the voters qualified to vote for a successor of such incumbent. The procedure to effect the removal of an incumbent of an elective office shall be as follows: a petition signed by voters entitled to vote for a successor to the incumbent sought to be removed, equal in number to at least twenty-five percent of the total number of registered voters in such city entitled to vote for a successor to the incumbent sought to be removed, demanding an election of a successor of the person sought to be removed shall be filed with the city clerk which petition shall contain a general statement of the grounds for which the removal is sought. The signatures to the petition need not all be appended to one paper, but each signer shall add to his or her signature his or her place of residence, giving the street and number. One of the signers of each such paper shall make oath before an officer competent to administer oaths that the statements therein made are true as he or she believes and that each signature to the paper appended is the genuine signature of the person whose name it purports to be.
§ 78.260, RSMo