No, termination always comes with some risk, even when the employment is at-will. While at-will employment allows either the employer or the employee to terminate the employment relationship at any time, with or without notice, and with or without cause, it does not permit you to terminate employment based on the employee exercising a legal right or belonging to a protected class (e.g., race, sex, religion, national origin).
There’s even some risk when the termination is for cause, because a terminated employee could claim that your reasoning is just for show, and that they were actually terminated for an illegal reason. That risk grows exponentially when you don’t provide the employee with a sensible reason for the termination.
Consequently, the safest way to terminate an employee is to have documentation that justifies the legitimate business reasons behind the termination. This documentation would include infractions of policy, instances of poor performance, and any disciplinary or corrective action taken. The more you can do to show that you had a legitimate business reason, the harder it will be for an employee to fill in the blank with their own illegal reason for termination, and the less risky it will be.