Next time use a two stage with extra coats of clear, and you can sand and buff your troubles away!

If it were a solid color, you could have done some sanding and buffing, but not on a metallic. This time you will need to clearcoat.... unless one of these other guys has tried sanding and buffing the metallic version of this product successfully?

If you do clearcoat, you'll need to rough the surface with gray scotchbrites, and use an adhesion promoter, before the clear.