Update Apple Id Settings requires iPhone passcode and I don't have the phone any more
My mac is showing in sys.prefs that I need to "Update Apple ID settings". When I click continue, I sign in with the apple id and then I am asked to sign in to the mac because icloud wants to make changes, which is fine and I sign in. THEN... I am asked to enter the 6 digit passcode I use to unlock my iPhone. Problem is, that phone was damaged a couple of years ago and is gone! I don't know what that passcode is and don't remember ever setting one anyway! So, I click 'Forgot Passcodes' and it says I can select another device to authorise this mac... but it doesn't offer me to use my ipad so I am stuck with only the one device, this old phone which as I say, is long gone! The only option it offers me is to cancel or 'reset icloud data', and if I select this it tells me that passwords, icloud home and stuff will be permanently deleted!
So! What do I do? How do I update these settings without having a second device? I deleted the iPhone from my account settings/devices, which now only shows this mac and my ipad.... but the update routine described above is still asking me to enter the passcode for the old phone and it still DOES NOT offer me to use the ipad instead!
Any ideas??
MacBook Pro 15″, macOS 10.12