If you have empty folders on the hard drive of your computer use the File Manager that comes with every OS to delete them, Win/File Explorer or Finder.
The point of the Source area of the import dialog window is so you can browse all drives and folders on the drives that are connected to your computer. It is kind of like opening the File Manager on your system. It displays all drives and folders.
But just because a folder is showing empty in the LR Import dialog window doesn't mean it is really empty. LR only shows image files. So those folders that don't have images in them may appear empty to LR, no images in those folders, they more than likely have something in them. In some cases important OS or program data.
Thankyou all done!