How can I permanently delete my Apple ID?

cannot imagine why you need to do it, but still:

1. Head to Apple’s data and privacy webpage login
2. Log in to the account you’d like to delete
3. Toward the bottom, click on Request to delete your account
4. Make sure you want to delete your account and double-check backups of your data
5. Double check if you have any subscriptions with your Apple ID
6. Choose a reason for deleting your account, click Continue
7. Follow the remaining prompts to permanently delete your Apple ID account

All purchases made using an Apple ID are tied to the ID. Delete the ID and you will need to download them using your new ID. There have been posts by people who have contacted Apple Support and they were told that if you delete an ID associated with an email address, you can never reuse the email address for an Apple ID.  Make sure you sign out from the places in the link before deleting the ID. If you fail to sign out of your device before deleting the ID, the device may become useless.

What to do after you change your Apple ID or password - Apple Support