Mo. Rev. Stat. § 274.080: Articles of incorporation may be amended.

The articles of incorporation may be altered or amended at any regular meeting or any special meeting called for that purpose. An amendment must first be approved by two-thirds of the directors and then adopted by a vote representing a majority of all the members of the association voting thereon. Amendments to the articles of incorporation, when so adopted, shall be filed in accordance with the provisions of the general corporation law of this state.