You may have noticed the new "Archive" button on the Trainee Tab in Training Tracker. Now you can move employees that are no longer with your company out of the active reporting, while maintaining their records for auditing purposes, or in case they return to the company.
Archiving is slightly different from making a task inactive. An inactive task remains on the Tasks tab, and shows up in reports on the Assignments tab, but cannot be assigned as part of a new task. Archived trainees are removed from the trainees tab, and their assignments are removed from the assignments tab, unless you specifically choose to view them.
Archived employees (trainees) can also be brought back, or un-archived, along with their training, if they return to the company.