How do you delete your saved game and start over in Pokemon Black/White? I don't see the option anywhere.
Since the collectible-ness of Pokemon is a big part of the game, the creators tried to make it intentionally difficult to delete your data.
In order to do it, go to the main screen of the game (where it shows the legendary and tells you to press start) and press Up, Select, and B at the same time.
This will bring up some menu options that will be able to delete your game. Make sure to take your time navigating these menus if you're serious about deleting, because all the defaults will abort the delete.