There is only one way. You must:
1. f*** a mime (in game)
2. eat cereal (in game)
3 go to the title screen and hole up, select and b.
Chat with our AI personalities
pres up star and select at the top menu
u cant. u have to delete the first file in order to create another one.
In order to delete a save file in Platinum, start your Platinum game and go into the title screen aka the screen where it shows Giratina at and where it says "Press Start." Next hold down the B button, the Select button and Up on the D-Pad all at the same time, it'll ask you if you want to delete the current file then.
you can't
On the title screen, press Up, Select and B together. This will permanently delete your file.