Any ideas how to remove paint from an outside electric box?

When we bought our house the previous owners had painted the gas and electic meter box (you know the plastic ones outside the front of the house) brown. The paint is peeling off in bits and well looks horrid and as we are going to be putting the house on the market - want it sorted out.n

So any ideas how I would remove it or would it be best just to buy some more brown paint and paint over it? If so, what paint would I use?

Thanks