Hi there
If you want to delete the account associated with an Apple ID you must first change that Apple ID See this on how to do that
How to change your Apple ID to a different email address
- Go to appleid.apple.com and sign in.
- In the Sign-In and Security section, choose Apple ID.
- Enter the email address that you want to use as your Apple ID.
- Choose Change Apple ID.
- If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email.
- If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID.
If you try to change your Apple ID to an @icloud.com email address that was created within the last 30 days, you will be asked to try again later.
If you see a message that the email address you want to use isn't available or is already in use, check that you or a family member aren't already using that email address with a different Apple ID. If a family member is using that email address, remove it from their account then try to use it.
In some countries or regions, you can use your phone number as your Apple ID. But if your Apple ID is an email address, you can't change it to a phone number.
If you want to create a new Apple ID, it is not possible to merge it with your old id. So make sure that everything you have in iCloud is also on your device(s) and cancel any subscriptions, you will need to subscribe again with your new ID. Also any app purchases you've made are not available on your new ID