My old xbox account has a email that nolonger exists. I can't log into the account nor...

Well, no, because the Xbox account didn't exist until I made it. I could have used this email as the alias for my old account had I not mistakenly signed up for a new Xbox account with it. I made the Xbox account, so why can't I delete it from existence, and then use this email as the alias for my old Xbox account?

The email account I've deleted isn't the account used for my live address (which is a hotmail one).

The deleted email account was an old address I had used for the security proofs (the only security proof that was setup and was jm****@bt****.com).

Effectively I can't add any new proofs for 30days until they all reset.

I can't stop the reset of the proofs because it wants to send a verification to the non-existent email address.

I can't access the old security proof email address (the account has been deleted).

I can't log in to xbox live due to be unable to add new proofs.

I found out that the email has been changed but I cannot do anything because it says that my microsoft account doesn't exist, so I can't change my email back to my original one nor change the password

I was about to do this, but have a question. At the permission screen, it asks for parent email at the bottom. Then, it goes to a log in for the parent account. Once the parent signs in, it shows the previous "parent email" as what the sign in will be. Is
this the email log in the child will be using to sign in to Live? Should it be the same as my existing Xbox Live email log in or must it be different? Can't it just be their email for the sign in? My other concern is it messing up my almost 10 year old Xbox
Live account by doing this incorrectly and the process for this is not very detailed.

No we can't log into the email that has the account gamertag associated with it. Nor can we log into the Microsoft account....

The only place the gamer tag is logged in is the Xbox.

So then saying log in add a new alias doesn't work cause we can't get a code.

They want us to remember subject lines of emails from an outlook account we haven't used in years