@hrefna From https://en.wikipedia.org/wiki/At-will_employment :
"... at-will employment is an employer's ability to dismiss an employee for any reason, and without warning, as long as the reason is not illegal (e.g. firing because of the employee's gender, sexual orientation, race, religion, or disability status)."
Employers have very broad discretion to fire people who have been hired under at-will employment.