Itunes wont sync new Iphone 5c?

Yesterday i got a new iphone 5c and i had to set up a new itunes account, so i understand that my old music from a previous account wont sync, but how do i get rid of it? I need to sign in on my new account so i can start putting music on my phone. But all the songs from my old account wont go away, even when i sign out and sign on to my new account.help!

There are the steps you need to follow.
From old iPhone you must have created a backup in iTunes library, when it asked for it. Or, do it now.
When you connect with iphone 5c, you should be able to find a prompt asking for whether you want to setup completely new iPhone or restore from your previous backup, this belongs to your itune library that already exists. Sign in your account authorize iphone, update softwares that you already have for iTunes, and iOS 7.0 which is already out. Then, connect iPhone to iTunes and follow the prompts

Itunes will not load all my music to iPhone 5c