Instructions
Launch either "HeartGold" or "SoulSilver" on your Nintendo DS.
Highlight "Connect to PokeWalker" on the main menu.
Press "A" to enter the PokeWalker Connection menu.
Press "Down" on the directional pad and the "X" and "L" buttons at the same time.
Select "Yes." The Pokemon currently stored on the PokeWalker is removed and the PokeWalker is reset back to its original factory settings.