You report you are running Ventura. Connect your phone to the computer (not sure this is necessary). On your computer go to settings. Select yourself at the very top of the list ("Apple ID" words are under your name). In the middle of the screen begins a list of your devices, select your phone and select delete after a short pause (if you have a newer phone, make sure you are deleting the right one).
On Ventura, MUSIC replaced iTunes and iTunes does not work under Ventura. To update your account info for iTunes store, open MUSIC and select Account from the menu bar, then select account settings. Then look for Downloads and purchases in middle of screen and select Manage Devices. Delete old device as appropriate.