You can reset a Trainee by navigating to the Series Trainee Tab. Checkmark box next to trainee names, then click “Trainee Actions” and click "Reset" for the selected trainee you wish to reset.
If you just need to reset them for the Course within the Series, click the name of the trainee. Next, click the Reset button next to the course they need to be reset. This will only reset the course and not the entire Series.