Heat is your best friend when removing those letters.
Don't be suprised if you can still see the outline of them in the gelcoat.I went thru that,wet sanded and buffed but can still see it..
Paint-stripping heat gun (be very careful), a plastic putty knife, and WD-40 to remove residual adhesive. Hair dryers work. A spotlight may work faster. Heat lamps work quite well. Don't use a flame.
i'll second the heat gun. it works good. just be carefull like advised. bet ya could start a fire with a heat gun. then i opt for a razor blade(being very carefull to get the sticker and not the gel coat) to get the sticker started to be removed (a plastic putty knife sounds like a good idea too). then my fingers and pull it off. if it breaks, more heat and start the process all over again. i'll also second the goo off to remove the sticky glue. or finger nail polish remover has worked well engough for me too.......as for the outline left by the stickers. more goo off or finger nail polish remover then just used plain ol boat wax and rubbing and the outline has gone away.....