First, invent a time machine.
Second, go back in time and force Apple to add account removal.
For now - you can’t.
You can remove your Google account. You can remove your Facebook account. You can’t remove your iCloud account and your Apple ID. They are eternal.
I’ve run into this little oddness before, but I was reminded of it when cleaning up my deceased father’s online presence.
A 2013 Apple forum post says: “Access can be stopped by Apple if they are provided with your Death Certificate.” I bet you have to fly the certificate to Cupertino. Even then it’s not clear if any data is deleted. I wonder if anyone has ever done this.
Apple gets away with a lot.
PS. I did set his email to forward to me.