Turn editing on, then the icon of an eye will show. If you have role of "Course Editor" or "Teachers" you will have the permission to hide sections. For example a "non editing teacher" do not have the permission to change the course and therefor restrictions on hide sections.
If you need to do this on a course please ask you Company Manager or Company Department Manager to give you the roll of a Teacher in the specific course.
Remember that a Teachers roll normally only are related to just one course, so if you need permission to do this I all courses in your company, that needs to be set up by your Company Manager or Company Department Manager.
Who can't hide sections in a course?:
Manager - Yes
Course creator - Yes
Non-editing teacher - No
Student - No
Guest - No
Authenticated user - No
Teachers - Yes
Company Manager - Yes
Company Department Manager - No
Client Administrator - No
Client Course Editor - Yes
Client Course Access - No