Spray paint on rocks is sometimes difficult, although not impossible, to remove. If the rock is porous, you'll need to do a lot more scrubbing after using the appropriate removal product. If the rock is decorative and has been polished, removal is easier. No matter the rock, many products have been designed specifically for spray paint removal. You'll find these—as aerosol sprays and other forms—at most hardware and home improvement retailers.
Put on a pair of regular household rubber gloves to protect your hands from the spray paint removal product. If you are working outdoors, you shouldn't need a respirator—however, if you are working in an enclosed area, consider using a painter's mask, even if the product you use is low-fume (in addition, don't do this around open flame).
Apply graffiti remover to the stone. These are either sprayed on or wiped on with saturated wipes or a sponge. Whichever kind you use, cover the paint well with the product.
Give the product some time to work. How long you'll need to wait depends on the product.
Scrub the area with a scrub brush. You'll have to scrub hard if the stone is porous. If the stone is highly polished, you might get by with using the abrasive side of a kitchen sponge.
Use a wet sponge to wipe the remaining paint off. Rinse the sponge several times so the paint doesn't simply smear. Rinse the stone if the product requires it—some do.