How cleaning graffiti painted on a stone?
Step one: in the contaminated area spraying some "VD glue clear" and "VD color Remover".
Step two: use the small round pad for cleaning.
Step three: look somewhat like, clean surface with damp cloth and dry.
Step four: after drying if you feel not satisfied, spraying and cleaning up more than once.
Step five: If you want to prevent sprayed with words, you can use high quality coat of oil on the surface twice. Even after being sprayed, use wet towels to wipe off.