PDF document frozen on screen

Hi there, I recently tried to move a PDF document into a folder on the desktop, but it froze on top of the folder. Now it is at the front of the display so it is visible even when on fullscreen mode. I have tried deleting the document but cannot click on it and am unable to delete it from finder. It is also permanently highlighted. I have tried restarting the macbook aswell. Wondered if anyone has had this before?