Unfortunately for security reasons accounts cannot just be deleted on request. In order for those accounts to be deleted you would need to know the password.
I would suggest you try the password ***** tool here http://www.pof.com/getpassword.aspx
Once you recover the passwords you can go to following page to delete them: http://www.pof.com/deleteaccount.aspx
You will need to go through this process for each account you wish to delete. As I am sure you understand accounts cannot just be deleted without the password. This would make it easy for people to simply delete others accounts without the authority to do so.
If you are unable to reset the passwords and cannot remember your email address you used to create the account log into your main account and go to the following page:
Next scroll to the bottom where it says Plentyoffish Help Section and create a post explaining that you need the duplicate accounts deleted but cannot remember the email address you used to create them, a moderator should reply back and instruct you further.
Before you go please do me a favor and take a moment to rate my service by clicking the stars above, 3 or more is very appreciated, we can still chat after rating if you need more help.