You can change the iCloud account on your iPad by signing out of your old account and into a new one, or add a different account for app purchases.
Keeping your Apple ID email current is a crucial step in maintaining the security and functionality of your Apple account. Whether your email is outdated, compromised, or no longer accessible, ...
To block emails on iCloud, you'll need to use the iCloud website — you can't use the Mail app on your iPhone or iPad.