When I've gotten sharpie or permanent marker on my skin and needed to get it off I used some rubbing alcohol on the spot where the sharpie or permanent marker marked my skin.
Dip a rag in some rubbing alcohol and rub the mark with the rag and the sharpie mark or permanent marker should come off your skin.
You can also use some acetone or nail polish remover on the sharpie mark and it too should remove it but the rubbing alcohol works just as good.
Then just wash the area again with soap to remove the rubbing alcohol smell or acetone smell from your skin.