Yes, I did delete the DCS folder (I originally had it installed to Program Files) I also did some registry scrubbing with CCleaner just in case. Only one rogue entry was in there for DCS.
I did try the patch 2 default key file, but ty, good to know I can delete that versions installer and move on to just trying from 4.
With my current install, I did an uninstall, then manually deleted the folder and reinstalled. No copy pasting of older files, etc.