How can I change my icloud email address

The main address on your iCloud account - something@icloud.com - may have additional versions (i.e. with the same text before the '@') of @me.com and @mac.com, depending on how long you've had the account. Apple refers to these alternatives as 'aliases'; you cannot change them.

Once you have created an iCloud account and chosen an @icloud.com address to go with it you can't change the address (short of creating an entirely new account).

However, all is not lost. You can add up to three 'email aliases' - these are additional addresses (not accounts) which deliver into the same inbox as the main account. (In fact it's a good idea to give out alias addresses, rather than the main address, because if they attract spam you can easily change them.)

You should be aware before you start that once you've created an alias you cannot turn that address into a full iCloud account or move it to another account.

More information on aliases here: Add and manage email aliases for iCloud Mail on iCloud.com - Apple Support

Depending on if you want to use a different ID, you can sign out and in or if you want to fully change your ID.

Check this article: Change your Apple ID - Apple Support

I believe you can fully change your Apple ID to a different email according to the support page I posted above.

You can change the email address which forms your Apple ID. You can't change the @icloud.com address you created when you first opened an iCloud account.