Have you had to remove one of your course modules due to lack of time? In order to hide both the module and all of its content from your students you will need to:
If you do not unpublish the individual items in the module, then those items will still display on the course calendar, the course "To-do" list, the Gradebook, the Assignments page, and the Assignments list at the bottom of the Syllabus page. This means that your students will see that these items are due, but because the Modules act as gate keepers, students are unable to access these assignments. For more information on how this works and directions for un-publishing module items, see How do I use Draft State in Modules?