I'm not sure there's a way. You could TRY going to "help" in scrapebox, then click reset all settings. That might do it, I'm not willing to try it though I don't want to lose my footprints.
EDIT: I stumbled on how to do this. Open up the "configuration" folder and open up the footprints text file, delete the ones you no long want and save it and start up scrapebox, they should be gone.
EDIT: I stumbled on how to do this. Open up the "configuration" folder and open up the footprints text file, delete the ones you no long want and save it and start up scrapebox, they should be gone.