When you delete a course collection, only the collection is deleted, not the courses contained in the collection. In addition, no people are unenrolled from any of the courses in the collection.
To delete a course collection:
1. Click Courses on the top main menu.
2. Click Collections.
3. Find the collection you want to delete and expand it's details by clicking the "+" next to it's name.
4. Click the Delete link on the right side of the expanded details.