Ending Checklists after employee terms

Summary

Need to end tasks once an employee is terminated.

Content

We have an onboarding checklist that includes checklist tasks for the managers to provide feedback at 30, 60, and 90 days after the employee's hire date. We've run into a problem where the task reminders/notices continue to be triggered even when the employee is terminated prior to the task. For example, someone is terminated on day 50, and the 90 day task still triggers from their onboarding causing the Manager to get notified that a review needs to be completed. 

Is there a way to end all of the delayed onboarding checklist tasks when the employee terminates? Or is there some other way to make the system stop sending notices once the term is processed?