Remove an iPhone from my Apple ID?

Hello there,

I just bought an iPhone 4S and it's an amazing phone. Now I'm going to sell off my old 3GS so I was looking for to remove it from my Apple ID since I won't be the owner of it any longer. Where can I do this? It feels like I've checked everywhere but I can't seem to find any solution.

I found http://support.apple.com/kb/HT4627 which states:

" Removing an associated device or computer from an Apple ID

To remove a device or computer from your Apple ID:

1. Open iTunes.
2. Sign in to your Apple ID by choosing Store > Sign In from the iTunes menu.
3. Choose Store > View My Account from the iTunes menu.
4. From the Account Information screen, click Manage Devices.
5. Click the Remove button next to the device name you would like to unassociate. "

Now the problem is when I sign in and view my account I don't have anything called "Manage Devices" shown in that area. All I got is Apple-ID, Payment Info, Billing Address, Region, Computer Auth., Purchase History, Ping and Settings with Nickname, Reviews, Alert Me, Rec & Ping Posting + Passes. There is nothing that says Manage Devices.

So, anyone know what I should do? Since I will be selling of the 3GS I don't need nor want that phones serial number to be connected to my Apple ID any more.

Thanks in advance for any help.