There are a couple of removers made for decks and they are made by the Flood Company and Wolman. They work fairly well but it depends on the type of coating(deck enamel or a stain) on your deck as to how well they will work.

Thanks for the info.

Sanding treated lumber is just fine as long as you are careful not to breath the dust and wear protective gloves and clothing when handling it.

Sand away.

It's cheaper, faster, and less messy than removers.