Remove Silicon from Gelcoat

[98Prostar205]

I am replacing my exhaust flanges on my 98 prostar 205. I got the old ones off. Now I need to remove the old silicon type stuff from the gelcoat. What is the best method? Also, the old ones had this silicon stuff on the inside diameter of the holes in the transom. How do I reapply new sealant in this area when I get ready to install the new flanges?