City of Rocks graffiti

I was climbing on the Anteater this morning, looked down and saw big yellow spray paint "I LOVE <3 + J" painted on a boulder near Morning Glory Spire.
From the gramer I'd say the artist is in 3rd grade.

I know that that best way to clean up sand stone is with a grinder and take off the top layer and leave a smooth finish.

How would you go about cleaning up granite? It's the grainy kind, non-polished, super textured, with liken growing under the paint.

Elephant snot and water is what is being used on the Little Cottonwood Granite with good successes. Talk to park before embarking on any clean up first.