Instructions
Insert the "Pokemon Black" game cartridge into the Nintendo DS.
Press the Nintendo DS power button to turn it on. Select the "Pokemon Black" icon to start the game.
Hold down on the directional pad, the "B" button and the "Select" button at the title screen.
Select "Yes" to delete the old save file.
Press "Start" to go to the options menu and select "New Game" to start a new file.