What would you do if you walked up to ride to find out that it had been vandalized? Spray paint vandalism can and will ruin the finish of your vehicle's paint if left to dry and stain.
Try this first: Butter wet wax. This also works well for black rubber marks from shoes (or burnouts)
If that doesn't work you can step it up to this:
Nick goes over a few tips on how to best remove this type of dried paint. Using the natural cleaning oils of Butter Wet Wax to gently lift off of the surface. If you are ready to cut through swirls and scratches, use your favorite machine polisher with a Microfiber Pad with a combination of V34 Hybrid Compound, V36 Cutting Polish and refine the finish with a White Hex-Logic Pad and V38 Final Polish.