Instructions
Start up your PlayStation 3 and log in to the account you want to delete by selecting it from the main menu.
Highlight the active account by scrolling to the left of the media bar where all users are displayed. The user account will have a white dot next to it when highlighted.
Press the triangular button on your controller to bring up a sub-menu. On this menu, select the "delete" option. You will be asked to confirm your action. Select "confirm" and your account is officially deleted, along with any saved data that was once associated with your account.