Hold down "L" and "Start" as soon as you see the Game Boy Advance logo (or before you turn on the power.) Keep holding and a prompt to delete the data will appear. You then must choose which language you would like to use.
If you have Sonic the Hedgehog 2006 for the PlayStation 3:Press up when having the controller icon selected. Search for a folder for various save data. Then press the triangle button to bring up...
You go to run. Type %appdata%, then into the Roaming folder, into .minecraft, then saves, then pick the world you want to delete, right click and delete.