[iMore Question]

I have two iphones bought before o2 ceased to provide email services. I cannot now delete this o2 username to replace with a current email address. I cannot trade in my older iPhone until I have deleted the account.
How can I change the locked username?

[Just_Me_D]

I have two iphones bought before o2 ceased to provide email services.

Okay

I cannot now delete this o2 username to replace with a current email address.

Why not? Can you not go to Settings-Mail, Contacts, Calendars and tap on the O2 account, and then select "Delete Account" at the bottom?

I cannot trade in my older iPhone until I have deleted the account.

If you go to Settings-General-Reset and then select "Reset All Contents & Settings", your device will be restored and set to used like it was when you first took it out of its box.

How can I change the locked username?

What locked username?