When you view a need folder in the Need Folder Properties page,
you can delete it by pressing the "Delete" button at the bottom of the page.
See the preceding topic called How To... View All The Details About One Need Folder.
You'll want to heed the warning that MakeLifeEasy presents to you:
when you delete a need folder, you permanently delete all folders and needs
within that folder, and all its subfolders, and all assets that ever covered those needs.
It's a major operation.
Usually you'd only delete a need folder when you entered it by mistake,
or if you've moved all its subfolders and needs to another folder first.