You can activate or deactivate any teacher in the organization from the Manage Teachers page.
You can activate or deactivate teachers by clicking the toggle bar at the right bottom corner of the particular teacher's box. You will see an alert box while deactivating the teacher with the following message.
Note: If a teacher is already enrolled in a class, they cannot be deactivated. Instead, a warning message will be shown while deactivating or deleting the active enrollments for the particular teacher.