To delete all content from the Content tool in D2L, please follow the steps below.
Click Content on your course navigation bar.
Click on Table of Contents in the left Navigation pane.
Select Delete All Modules from the Table of Contents drop-down menu.
Select Permanently delete all modules, topics, and all associated files and activities from the course, then click Delete.
It may take some time for the process to finish. Once completed, all items will be deleted from Content.