Turn on your DS and click on your Nintendogs game above (or if you set your DS to auto mode, skip this step). If the game loads before you press the buttons, this will not work. The buttons must all be held down simultaneously to reset the game. Try using the sides of your fingers if you're having trouble holding them all down at the same time. Remember that once you delete the game, you will lose your dogs, trainer points, and money. Once the file has been deleted, there is no way to get these things back. Make sure you really want to lose all your progress.  Click "Yes" and your game will be deleted. You can now begin a brand new game, as though you just took it out of the box. If you change your mind, just click "No" and you can continue your game.

TL;DR in Indonesian:
Masukkan gim Nintendogs ke konsol DS. Tahan tombol L, R, A, B, Y, X ketika layar putih bertuliskan Nintendo muncul. Pilih "Yes" (ya) saat ditanya apakah Anda mau menghapus gim Nintendogs saat ini.