It would appear that Capcom has discovered an exploit in the 3DS' cartridge system and will be employing it in Resident Evil: The Mercenaries 3D, possibly to make sure gamers are tied to its product via an unbreakable chain. In short, you can't delete your saved games.
The information was spotted in the game manual, which came with the warning, "Note: Saved data on this software cannot be reset."
It's been proposed that Capcom did this as a way of combating used games, essentially making a secondhand version of the game useless to new players who want to start from scratch. Until that's confirmed, I'll hold off on reaming Capcom out for being pointless, short-sighted dicks.
On that note, Capcom is yet to comment.