How to delete an old iCloud account after changing Apple ID

Jason. Thanks for your reply.

I had already read these articles, but they don't help.

SEems to be an Apple Gotcha ! i haven't forgotten password but changed Apple ID. However, Apple doesnt seem to have fully implemented this and whilst most of the new device works on the new Apple id, it keeps asking me to sign in to ICloud using the old Apple ID. But neither old or new passwords worked as the old apple id gone.

BAsed shed upon other internet sites where people had this issue (over multiple years) I recreated the original Apple id afresh, with a new password. This new password seems to work for signing in to ICloud - but is still not accepted to get signed out of iCloud to expunge from device

so no further forward at all

So finally got out of this gotcha - which Support Chat couldn't fix. Not sure this is a good solution but how finally worked for me to get out of the iCloud mess after changing Apple ID

Setup new dummy Apple ID using old email address - not used for anything

This still didn't allow me to sign out of iCloud on the new iPad as tried to delete the account and said "AppleID or password invalid)

The breakthrough was realising that as sign-out wasn't just signing out but deleting the account, I hard powered down the old iPad on a whim

Suddenly got a different (equally meaningless) message trying to sign-out of iCloud on the new iPad - but it did in fact sign out this time

Finally changed apple Id for iCloud in new ipad. So if in doubt try hard powering off the old device to get out of the picture entirely