Mo. Rev. Stat. § 486.310
If any notary public no longer desires to be a notary public, he or she shall forthwith mail or deliver to the secretary of state a letter of resignation, and his or her commission shall thereupon cease to be in effect. If a notary public resigns following the receipt of a complaint by the secretary of state regarding the notary public's conduct, the secretary of state may deny any future applications by such person for appointment and commission as a notary public.
(L. 1977 H.B. 513 § 24, A.L. 2004 H.B. 1193)