How do I delete an account?

You can deactivate or delete an account. Apple recommends doing the first for the obvious differences noted below.

How to deactivate your Apple ID account  https://support.apple.com/en-us/HT208503

If you request account deactivation, you'll receive a unique alphanumeric access code. When you're ready to reactivate your Apple ID, contact Apple Support, provide your access code, and we’ll help you reactivate your account. If you lose this code, we won't be able to help reactivate your account." 

How to Delete your Apple ID Account https://support.apple.com/en-us/HT208504 

“While your request is being processed, you can contact Apple Support with the unique alphanumeric access code you received, and we’ll help you cancel your request. After your account is deleted, Apple can't cancel the request, reopen your account, or restore your data.”

You can get additional information on both by signing in here: Data and Privacy https://privacy.apple.com/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.