Use a spudger or the tip of your finger to carefully disconect the orange click wheel ribbon from the logic board.

Use a spudger to pull back on the small black plastic tab holding the click wheel in place.

Continue to pull back on the black plastic tab, use your other hand to press down on the click wheel, and begin to slide it out of the iPod.

It's important to press down on the click wheel as you slide it out. Otherwise, the click wheel could be scratched by the iPod's metal casing.