okay, so my boat had a "home made" deck extension on it when i bought it used. it worked fine until the board used started to get weak over time. i took it off but there were some holes in my fiberglass from where it was mounted so to just "cover" the holes i put some white marine silicone in them. it actually looked great and could hardly tell anything was there until just recently it has started to yellow a little bit. how do i take the silicone off? i am going to fix it the right way this time but don't want to damage anything when taking off the silicone. thanks for any tips.