Current message going to old phone
I have a new iPhone with a new number through a new provider. My messages appeared on my old iPhone. I then removed the old iphone from my known devices, signed out of all devices signed in with my Apple ID and changed my password but the messages are still appearing on the old iPhone. I do not have access to the old iPhone so I need a way to stop this from happening without having the iPhone. Please help!!!!
iPhone 12 Pro Max, iOS 15