How to remove decal?

Heat is your friend but be careful being that it's on fiberglass.

I own a vehicle graphics business. The adhesive remover you want to use to clean it up really fast and really good without hurting the paint is called Rapid Remover, after you get the decals off. \
Here's a link. It is worth every single penny, trust me, especially if you are removing and cleaning up quite a bit.
Spray it on, wait a minute or two then use a plastic scraper or firm squeegee to scrape off the glue followed by paper towels. Then wash it off right afterwards with soapy water.

[ame="http://www.ebay.com/itm/like/130537813605?lpid=82"]Rapid Remover Adhesive Remover for Vinyl 32oz Sprayer | eBay[/ame]