How can I remove a PDF file from Mendeley Web, but keep it linked to my library in Mendeley Desktop?

I need to remove PDF files from my Mendeley Web library, but I have them saved locally on my computer and I still want them linked locally to my Mendeley Desktop library. It seems like if I delete a file from the Web, it is also removed from Mendeley Desktop (but not deleted from my computer). I don't want to keep my PDF files online. Thank you.