KYou can deactivate any lesson in your course:
To re-activate the lesson click Activate in the toolbar.
When you deactivate a lesson, it will become completely hidden to any learners and cannot be accessed or entered by any learner, even if they did enroll to the course it in the past. Disabled lesson is also excluded from the course progress calculations.
Note: You can deactivate and activate a lesson as often as you want.