* Save Data is Permanent: Pokémon games save your progress directly onto the game cartridge. There's no way to delete individual save files within the game.
* No Deletion Feature: There's no built-in option to erase your save data within the game itself.
What You Can Do:
* Start a New Game: You can always start a new game, which will overwrite the existing save data.
* Format Your Cartridge: This is the most drastic option. You can format the cartridge using the "Format" option in the Nintendo DS's "System Settings." This will completely erase all data on the cartridge, including your save files. Be warned, this cannot be reversed!
Important Note: Formatting your cartridge will erase all your save data for all games on that cartridge. Consider this action carefully.