Things You'll Need
Commercial paint remover
Latex paint is a water soluble formula that can be blotted up easily when it is wet. Any damp rag or cloth will wipe away wet latex paint easily on stone, but once latex paint dries, latex paint removal becomes an entirely different situation. The resins and polymers that hold latex paint together must be softened first before removal of dried paint. This can be done by using chemical- or petroleum-based detergent formulas, or very high heat.
Turn a heat gun on it lowest setting and literally melt the latex paint. Once melted and liquefied, wipe it off with a rag.
Cover the latex paint with a rag dipped into isopropyl alcohol. Keep the rag soaking on the paint, and the alcohol will slowly turn the paint moist and soft.
Coat the latex paint with a commercially-made latex paint remover. Use a rag to dab the cleaner onto the latex paint stain. Allow the chemicals in the remover to soften up the paint, then use another rag to just wipe it away.
Always wear gloves whenever you are using any chemical to remove latex paint.