Missouri follows the Employment-At-Will doctrine. This means that both the employer and employee can terminate the employment relationship at any time and for any reason, as long as there is no employment contract to the contrary, there is no discrimination under civil rights laws (based on race, color, age, national origin, religion, ancestry, sex, or physical/mental disability), no merit laws apply, or the state’s limited public policy exception does not apply. If you feel you have been discriminated against while on a job or while applying for a job, you have the right to file a complaint with the Missouri Commission on Human Rights.
https://labor.mo.gov/DLS/General/discharged