Instructions
Insert the memory stick into your PSP. The memory stick compartment is on the left side of your PSP.
Turn on your PSP.
Press the "Home" button if a game automatically loads. This will show you the main menu. If no game is presently in the console, the main menu will automatically load and pressing the "Home" button is not necessary.
Select "Settings."
Select "System Settings." From this menu, select "Format Memory Stick." You will be asked to select "Yes" or "No" to verify that you would like to format the stick. Select "Yes."