How do I close a PlayStation®Network account?
Once a PlayStation Network account is created, you can not delete it. It will remain on the PlayStation Network servers forever. If you wish, you may remove it from your PLAYSTATION®3 computer entertainment system so it is no longer visible.
Please note that if you delete a user, all game save data earned under this user will be deleted as well, be sure to copy any game saves you wish to keep to another user. Click here for information on how to copy games saves on the PLAYSTATION 3.
Closing a PlayStation Network account
If you wish no one to access the PlayStation Network account, you can also have it banned or suspended by Sony Computer Entertainment America (SCEA). To ban or suspend a PlayStation Network account, please contact SCEA Consumer Services' Accounts and Billing line at 1-877-971-7669.
Prior to having your account closed, you will want to deactivate your PLAYSTATION®3 or PSP® portable entertainment system from your PlayStation Network account. Click here to learn how to deactivate your system.
If you would like to use a new (different) account, you will have to create an entirely new PlayStation Network account.
Note: Purchased content cannot be transferred between different PlayStation Network accounts. We apologize for any inconvenience. If you do not wish to lose the items purchased with an account, you are able to edit the account information, as an alternative.
you actually can delete your PSN account. You have to reset your PS3 system default settings. But to warn you, it resets all your regular settings. When you do this it will tell you everything it resets before you continue but i put it all below straight from the users guide.
The one wanting their PSN account deleted must be logged into their PS3 system account
Go to Settings > System settings > Restore default settings