By quarter panel do you mean just the very corner of the dsco where the lights go or the full panel right back to the rear passenger door.
If it's the full panel you need to strip the interior and remove all the screws and bolts holding the panel in place. Once you've done that the whole panel can be peeled off (It's also held with panel seal). If it's just the actual corner you need an air saw to cut thru the tack welds that hold it onto the rest of the panel. LR only sell the full panel. So you'll need to phone around a few body shops to see if anyone does just the corner panel.