Instructions
Turn on your Nintendo DS with either "Pokemon Heartgold" or "Pokemon Soulsilver" in the game slot and the Pokewalker accessory.
Choose the option to connect to the Pokewalker from the options listed on the main menu. Keep both devices within two feet of each other to connect wirelessly.
Press and hold the X, L and down buttons when the "Save, then go for a stroll" text appears.
Confirm the option to reset the Pokewalker by selecting "Yes" when the game inquires. Navigate to the "Erase Pokewalker Records" potion and select "Connect" to completely wipe all records of the Pokewalker device.
Reset the Nintendo DS and Pokewalker and use the "Connect to Pokewalker" item to start the Pokewalker from the new game profile. The Nintendo DS will automatically import the new name linked to the saved progress of "Pokemon Heartgold" or "Pokemon Soulsilver" to the Pokewalker.