In the game minecraft what do you break the red stone with?

Doesn't really matter.

Redstone Ore can be mined with an iron pickaxe. Breaking redstone circuitry requires no tools and can be done barehanded.

Anything but TNT and water. TNT has a habit of permanently erasing blocks in general and water has the same effect but on redstone only.

The ore though requires an iron pick or greater (no stone or wood picks)

Redstone ore can be broken by an iron pickax or a diamond one. Using wood or stone can break the block, but you won't

Placed restone ore (ie the red piles) can be broken by anything.

Redstone blocks (the compact blocks made of nine pieces of redstone) can be broken and collected by a wooden pickax or greater.