If you have a method of homebrew you can try using GodMode9i to dump the cart's save. Then you can 0xFF fill the save with a hex editor and write it back. that should also reset the password and all other settings. GodMode9i requires a soft modded DSi/3DS or a DS/DS Phat with a slot2 flashcart.
EDIT:
Found this via google. There is a button combo you hold on booting the DS browser cart that lets you reset all save data:
L+R+Up+X+B+Select
(L and R = the shoulder buttons FYI)
Hold those buttons when booting the DS browser cart and it should give you an option to reset it.
EDIT: lol just now noticed that the person above me necro posted a thread from 2008....