old email address on iCloud

Hi, many years ago I setup my Apple ID with an email address. This also became my iCloud address when that got introduced. However about a year ago my email address got compromised so I changed email address for my Apple ID. However the iCloud still shows my old email address. And of course now the old email address doesn't have a correct password anymore as I changed email and password. The old password is not valid as it's changed and the new password is not valid as it belongs to a different email address. So how do I get rid of the old email address on the iCloud that is showing on my iPad? I'm only using the iPad locally so I don't even need iCloud on there but it keeps asking me for the password which doesn't exist. I've switched off iCloud on that iPad but it keeps insisting on that iCloud account and password. Anybody has a solution for that other than completely resetting the iPad?

Thanks in advance!