Linked military ipad Device Returned.

How do I Remove activation lock from my iphone that was linked to my military ipad for temporary use during covid, It ha since been returned. Now I have changed information and apple keeps sending the codes to the ipad that I no longer have possession of acount. How can I get this activation lock removed. Ive done everything asked and waited months to get authorization to change my account sign on and password which I did and then some codes were sent to the I pad to do the final whatever it is. I have done this several times. I've even cleared the provider release so I could change cell provider which has caused more issues as once the reactivated my sim it dropped my android and I was not able to get in my iphone. I had to go to a friends and call the new provider, (tmobile), It was aweful they had to send me a new sim for the android device and removed the sim activation on the iphone. I have had so many now juggled passwords back and forth plus the military on the ipad its a wonder i can keep any of the only one now that is correct That i remember but still apple sends the code to the ipad. I have given the imei phone number etc. all been verified. Help please I don't know what else I can do. Thank you