In general, students enrolled in a course will continue to retain access to that course even after the end date. However, you may have an old course that you want to prevent students from accessing (for example, if it has quizzes or other sensitive materials that you want to reuse). To address this, you can now select
Settings > Advanced > Block student access to this courseto prevent students from accessing that course. Nothing is deleted; uncheck that option at any time to restore student access.