Email address on icloud

It occurs to me that you might be talking about an @me.com or @mac.com version of the @icloud.com address, which you would have if you've been a member of iCloud's predecessors, DotMac and MobileMe. These have the same text before the '@' and are effectively the same address: you can't delete them.

If this isn't the case and you have only the @icloud.com address you can't change or delete it. If you have created additional addresses in the form of 'email aliases' you can delete those by selecting them in the Accounts list in the Mail preferences on the iCloud website and clicking the Delete link.

You say you don't use the email address anymore. Is it the email address, along with a password, you use in logging in to iCloud.com. If yes, that is your Apple ID. Perhaps, you don't use the email address, but I wouldn't delete my Apple ID. It is useful in doing many things. See this link: https://support.apple.com/en-us/HT202659 Anyway, why delete it. You could always sign out of your Apple ID. This reads cover what happens if you do: https://support.apple.com/en-us/HT208242 Do you still want to delete it. Ok, here's how: https://support.apple.com/en-us/HT208504

If you are using name@me.com, then the email related to your Apple ID is name@icloud.com. Why not just use name@iCloud.com rather than the first? I know that some would rather use the first for one reason or another. But, you don't want to use the first. So, again, why not use the name@iCloud.com?.

In any case, you can delete name@me.com from ever being used again, by anyone, by deleting your Apple ID account. Here is how to to so: https://support.apple.com/en-us/HT208504 Notice that the consequences of doing so are significant. And, note that your Apple ID is very useful: https://appleid.apple.com/#!&page=signin

Note also that changing your Apple ID will not solve your problem: https://support.apple.com/en-us/HT202667 This link says "If you use an @icloud.com, @mac.com, or @me.com email address as your Apple ID, you can’t change it to a third party email address. But, you can change it to an alias of your Apple ID address. For example, if j.appleseed@icloud.com is your Apple ID and you also have j.appleseed@me.com on file in your account, you can change your Apple ID to j.appleseed@me.com.

You can create a second Apple ID using a third-party email address, for example, name@yahoo.com. But while many have at least two Apple ID, this approach is not a good one and can lead to a variety of problems. I will leave it to you to search and to identify these problems.

See https://support.apple.com/en-in/guide/icloud/mm2a5932b3d4/icloud