Sandblasting paint is probably the easiest, albeit not the neatest, way of getting paint quickly off of a surface, especially if you need to remove large amounts of paint. Sandblasters can be expensive, though, so consider renting one, which you can do at any local hardware store. Sandblasting can also damage the surface underneath the paint, so make sure you do not mind if that surface becomes damaged while you are sandblasting.
Protect nearby items from sand and paint flecks by covering them with a tarp, newspapers or an old sheet. Secure with tape or bungee cords.
Protect your eyes and skin. Wear goggles, heavy gloves, long pants, boots and a long-sleeved shirt.
Close every valve on the blaster, including the lower sand valve, then fill it with around 40 lbs. of silica sand.
Twist the big air valve and the nozzle valve so that they are all the way open. Then, charge the tank, or pressurize it. Pressurizing causes the air to "push down" on the sand, forcing it out the bottom. Most tanks are pressurized electrically. For best results, plug your tank into a 20-volt circuit breaker. Then, simply flip the switch. When it is fully charged (watch the air gauge, which will read "full") open the sand air valve (different from the sand valve).
Point the nozzle at the paint, keeping it about 8 inches from the surface. Open the sand valve slowly. Spray with short, sharp bursts of sand for small areas. For large areas, use a sweeping motion.