Apple offers a Data and Privacy portal (https://privacy.apple.com) that allows users to download all of their personal data stored on the tech giant's servers. You can also permanently delete your account and associated data from all Apple services. For your security, Apple verifies all deletion requests. This process takes up to seven days. Your account will remain active while verification is in progress.
If your account is deleted:
- You won’t be able to access your iTunes, iBooks, and App Store purchases.
- Your photos, videos and documents stored in iCloud will be permanently deleted.
- You won’t receive messages sent to your account via iMessage, FaceTime, or iCloud Mail.
- You won’t be able to sign in or use services such as iCloud, iTunes, iBooks, the App Store, Apple Pay, iMessage, FaceTime, and Find My iPhone.
- Your data associated with Apple services will be permanently deleted.
- If you’re enrolled in the iPhone upgrade program, you must, of course, continue making payments for your device.
Before deleting your account, Apple recommends that you:
- Make a local copy or backup of your data. You can also get a copy of your data from the Data and Privacy site.
- Sign out of your devices and web browsers.
- Review your active subscriptions. They’ll be canceled when your account is deleted.
(This how-to is based on my experiences and info on Apple's support pages — where the images sometimes come from.)