How do I remove a subscription type that students use?

A type can only be moved to the trash if no student has a current or upcoming subscription of that type (a used-up or expired card does not count). Its card shows the number of students.

1. On each affected student's profile: Edit the subscription to give it an end date, or move it to the trash and add another one.
2. Then Subscription types > the type > Move to trash.

The type stays 30 days in the trash (it can be restored). Ended subscriptions keep their history.