Instructions
Start up the game on your Nintendo DS and select the "Other" option from the main menu.
Select the "Delete Saved Data" option from the available choices.
Scroll down the list of saved game files and select the game file or files that you wish to remove. Once you have selected the file(s), you can choose the "Delete" option to erase the file(s) from the game. There will now be open space for you to start a new game file from the main menu.