There's a "remove phone" option up on the left side of your account page. If it is listed as your primary fone you will need to change that before you can remove it. Also, that fone will forever have a relationship with your account. A csr can enter the s/n from that fone in their system and see that it had been in your account at one time. Back when I was selling oodles of fones the name and address on some of my accounts would change to the new fone owners info even after I had removed that fone from the account. I am not sure if that is an issue any longer as trac has shut down my selling hobby. Hell, I can't even keep a listing active on craigslist!
I recently tested the "don't mention a PP Dealer by name" rule here on PP Hofo......trust me, it is still in effect - got me a 7 day ban.