Use this procedure to delete unneeded categories from a project. 
If you delete a category that contains drawings, the drawings are deleted with the category. 
Note: Deleting a category from Windows Explorer may result in inconsistent project data. 
- On the Quick Access toolbar, click Project Navigator  . .
- Navigate to the tab for the category type you want to delete. 
- If you want to delete a sheet category, click the Sheets tab, and click  (Explorer View). (Explorer View).
- Select the category you want to delete, right-click, and click Delete. 
- Click Yes in the subsequent dialog box.