How do I erase Save data on Pokemon White?

Solution 1:

You need to press Up+Select+B on the Title Screen, which is the screen where you see the title ("Pokémon White Version"), and the cover Pokémon (Zekrom).

The Title Screen should look like this (taken from Pokémon Black via an emulator):

Screenshot of Pokémon Black Title Screen

Once you've pressed the buttons properly, the following screen should appear:

Screenshot of Save Data Delete Screen