If for some reason, a full course reset isn't possible, there is an alternative method for removing material from different parts of your course. Follow the steps below that correspond to the area in your course in which you want to delete content.
To begin, click on your course homepage and locate the Announcements widget.
Click the Announcements action menu and select Go to Announcements Tool.
Click the action menu for More Actions and select Delete.
Click the action menu from Table of the Contents at the top and select Delete All Modules.
Check the box at the top to select all the folders and files and click the Delete icon.