How to cancel Apple account?

So it does seem that you may want to delete an Apple ID.

To request deletion of the Apple ID you can visit Privacy.apple.com

Here is a good resource that will help you processing the request : https://support.apple.com/en-us/HT208504

Please note that When your Apple ID account is deleted, your account details and the data associated with your Apple ID are permanently deleted from Apple’s servers. You can't sign in to your account, and you won’t be able to access any data, content, or services that were associated with your Apple ID.

All content will be erased from your Apple ID.

Once deletion is finalized, you will not be able to log back in, and Apple cannot reopen or reactive your Apple ID.

Please review the section of the resource linked above name "Before you request deletion of your Apple ID"

Please follow those steps thoroughly as stated above "Everything will be erased from Apple Servers, and cannot be undone"

If you have any questions you can contact Apple Support : https://www.apple.com/contact/

Hope this helps