Removing decals from fiberglass requires a hair dryer, a bottle of Windex or WD-40, a soft plastic spatula, rubbing alcohol and a non-abrasive cloth. One trick is to blow-dry the decal for three or four minutes with a hair dryer to soften the adhesive under the sticker and avoid damaging the fiberglass.
After blow drying, spray the sticker generously with Windex or WD-40. Let it soak for seven minutes or until it is saturated. If it is a paper decal, look for the softening of the paper, and if it is a vinyl decal, look for the liquids seeping out of the edges. After the decal has soaked for a while, use the non-abrasive cloth to wipe it off. The cloth does not get every trace of the decal off of the fiberglass. Use the plastic spatula to remove any leftover glue or adhesive left on the fiberglass. To avoid damaging the fiberglass, avoid pushing or scraping too hard. Soak the non-abrasive cloth in rubbing alcohol, and gently wipe down the area to help dissolve any leftover glue or adhesive residue. It may be necessary to repeat some of the steps, but be patient, and be careful not to use too much force.