Remove Apple ID from old iPhone locked to owner

Read this article about removing Activation Lock --> How to remove Activation Lock - Apple Support To remove the lock you will need either:

-The account information that set the lock.

OR

-The original sales receipt from Apple itself or an Apple approved vendor. Other ways you may think might be “proof” of ownership or purchase, such as having the box or a receipt from a third party vendor such as Ebay, will likely not be acceptable by Apple. Apple may have no way of verifying the authenticity of other methods. If you have an acceptable receipt, ask Apple to unlock the device —> https://al-support.apple.com/#/additional-support