just removed the buggers from our beetle al be it 12mm but they are the same.
LOadsa penetrating oil and doudle nutted them well 90% of them if that dont work try a tickle of heat or get a few replacements and get a pipe wrench on them and theyll come out , if really tight try one way then the other when you get movement kepp winding back and forth with sum oil on the blighter and there you go.
oh yeah remember to keep the brake on too and in gear or the wheels going to spin.
jth
if no luck walk away and go to the pub and moan.