Deleting files but still no space on harddrive

Your photo files are not "in" Lightroom.

The photo files are on your hard drive, just like your documents and spreadsheets.

The photo files are referenced by Lightroom using the path and file names.

The references inside the catalog to your files takes up little space, so removing the photos from the catalog does not buy you much.

The things that take up the space on your hard drive(s):

The catalog (*.LrCat) file that contains all your edits.

The preview files used by LR to speed up the display of your files.

The optional smart preview files, used when your original image files are not available.

Your original image files.

The new image files created by exporting your edits.

The preview files can be deleted and LR will recreate them as needed.

Your original image files are important and should not be deleted. You can move them to a different hard drive if needed.

You need to restart Lightroom to have files delete fully. Lightroom tends to hold on to them just in case you need to undo. Empty Trash/Recyle Bin as well.