Head to Plenty Of Fish home page and enter username and password to login into your account.
Click on the “Help” button at the top right hand side of the screen.
You’ll find a list of options along the left hand side of the screen, tap “Remove Profile“.
On Remove Profile page, Click here, select to delete your account.
On the next page, scroll down and find “To delete your account”, CLICK HERE.
Now fill out all the details such as username, password, reason for leaving, how many dates with POF users did you go on, would you recommend POF to others and Click “Quit/Give Up/Delete Account” button.

Source : how to delete pof account on android