How do I change my iCloud email account

See the article Manage and use your Apple ID - Apple Support

Manage your Apple ID

Because your Apple ID is used across all your devices and services, it's important to keep your account information up to date. Simply sign in to appleid.apple.com2 at any time to manage your account:

• Update trusted phone numbers and devices that you're currently signed in to with your Apple ID.
• Change your password to help maintain the security of your account.
• Update your Apple ID email address3 to make sure it's an address that you use frequently.
• Add additional email addresses to help people find and communicate with you on Apple services like FaceTime1, iMessage, and Find My.
• Update the birth date associated with your Apple ID.
• Change your Apple ID country or region.

You can also learn how to manage your payment information on your iPhone, iPad, iPod touch, or Mac.

If you mean that you want to change your Apple ID to a different email address, see information in Change your Apple ID - Apple Support