edit your Apple ID and remove your old phone from trusted devices.
When you say edit?
Any link to remove the old phone?![]()
Sure, go to http://appleid.apple.com
log in using your iCloud credentials.
Then go to Password and security, and next click on "Trusted devices"
Chances are, your old phone is still there
However, for future reference, please note that if you sell the phone and the new owner sets it up with their own apple id, the device will disappear from your apple ID account. In your case, the phone is still there because you haven't restored it or no one else has activated it.
I went there and i did not found any trusted devices category. I had to make a 2 step verification. And so i did and now i dont see my old iphone there... only the new one. But in the text message settings (picture above) the old iphone is still there... i did a clean restore and the old iphone still exists. I remember that before i gave it away i did a clean restore on my old iphone... i know that it has not yet been activated from a new user......so?
This is a known issue that occurs if you restore a device BEFORE signing out of iCloud and iMessage on it. I have read that changing your Apple ID password will remove the device from that list. Otherwise, I am not sure how long it will stay there.