How to Remove Graffiti From Different Surfaces?

Try wiping graffiti with any common paint thinner (ex: mineral spirits, lacquer thinner, acetone), or try graffiti removal products such as “Goof Off.” Sometimes wiping the graffiti with light penetrating oil such as “WD-40” or “Three-in-One” will remove it.
If graffiti still remains, try to remove it by rubbing with steel or bronze wool, or light sandpaper.
If graffiti still remains, try power-washing it with a 3000psi pressure washer.
If none of these methods work, paint over the graffiti.

If the wood is not weathered and is sealed with paint, stain or sealer, try to remove it by wiping it with mineral spirits. If the wood is weathered, do not use this technique, as the mineral spirits will be absorbed by the wood, driving the paint further down into the wood.
Power washing with a 3000psi pressure washer can be used, however, observe carefully to make sure the pressure is not driving the paint deeper into the wood grain.
If these methods do not work, sand the wood and re-paint or simply paint over the graffiti.

Try wiping graffiti with a light, penetrating oil such as “WD-40” or “Three-in-One”. Do not use paint thinners as they can soften the plastic and can cause clouding (if clear plastic) or permanent tackiness of the surface.
Sometimes a light rubbing with ultra-fine steel or bronze wool will remove the paint.
If these methods do not remove the graffiti, paint over it.

The best option for this type of surface is to power-wash the graffiti with a 3000psi-pressure washer. Be careful in selecting the type of tip you use in the pressure wand. Too narrow of a tip (such as a 0 degree) will etch the masonry surface, leaving a perfect outline of the graffiti removed.
Sand-blasting is another removal option. As with pressure washing, be careful not to allow the sandblasting tip to remain in one spot too long as it can permanently etch the surface. Be sure to keep the tip moving over the painted area and the surrounding areas so that the surface is blended.
If power-washing or sand-blasting does not remove the graffiti, the next best option is to paint over the graffiti.

The best method for removing painted graffiti from glass is to use a razor blade to carefully scrape it off. This method is 99% effective. Use the razor blade in a holder and scrape at a 30-degree angle to the glass.
If the paint does not come completely off after using the razor blade, use ultra-fine bronze wool with water to gently rub the remaining paint off.
You can use paint thinners on glass, however the razor blade method is much quicker and more environmentally friendly.

Before you clean any graffiti, consider taking a picture in case you are ever asked for evidence of the vandalism.
The sooner graffiti is removed, the more the offending vandals will be discouraged. They’ll be less likely to return if the graffiti is promptly removed.
If you want to remove extensive aerosol graffiti from an unpainted surface, it may be best to have it sand or water blasted.