Minecraft World Edit remove certain blocks?

Is there a way in Minecraft with World Edit to remove certain blocks from the whole map at once?

// replace [block to be removed] air

You just have to do what Syrqx wrote on the whole map. There's no other option.

Removing blocks around the world will not work because the area has to be marked with a wooden ax. If your world has a boder and is limited, then you have to fly diagonally from one corner to the other and mark it. But think that's impossible with and without a map.

Then proceed as Syrqx has described.