I had an Apple ID related to an iPod Nano maybe… It was a very low threat as I had not used it for anything but the iPod years ago, in fact I used a program back in the day called Foola There was no data to back up, take out, delete or recover. This iCloud account had a recovery gmail account which I am slowly getting rid of associated accounts.
On a desktop, using Proton VPN and Brave.
I signed in after recovering my password using the gmail account. Denied the option to upgrade to two factor authentication.
Edited all my personal information and payment information. Found an expired credit card changed the payment option to None.
Used a random persons information in a different state as my information.
Changed all the security questions to simple 4 digit random passwords.
Used a MySudo number in case I have some problems logging back in. Deleted the gmail account as a rescue email. Surprised I could just delete it.
Logged out and logged back in. Found the edited information had been changed. The phone number was not required or validated.
Deleted the MySudo number and replaced it with the alias phone number.
Went to privacy, manage my data, logged in. Went through the process to delete the account. This required a verified email or a phone number for account recovery. I used the SimpleLogin email. Got a verification code and then signed out.
This might be overboard just to delete an account due to association but if you need to this is how I went about.