Xbox account to other account

I went to do this, but my son already has a Microsoft account using his email address. How do I do this?

if you sign into your Microsoft account online you can sign in and set up a secondary alias (sons email) then make that email the primary email address. you will be able to keep your email address.

Hello Guardiola1980,

Thank you for posting on Xbox Forums. In regards to this issue/question of wanting to transfer the Xbox account from one email address to another, does your email that is currently connected to the Xbox account have the domain of either @hotmail or @outlook?
If yes to either one, then it won't be possible to remove the email address associated with the Xbox profile as that would delete the email address permanently.

If it ends with any other domain name such as @gmail, @yahoo, etc., then you should be able to add a new email to the associated account and then remove your email address thus disassociating your email address from the Xbox Account. For more information
on how to do this please view this support article for Changing your Email Address.

You don't necessarily have to remove your email from the account you can just make your son's email the primary for the account and have your email address as a secondary email just in case.

If you have any other questions please feel free to reply back letting us know. Thank you again for posting on Xbox Forums.

If your son already has a Microsoft Account, then it's not possible to transfer "your" Xbox account to your son, I'm afraid.

Hi there, looks like you might have an expired payment method and it still gave you a month of your subscription without you actually paying. To make sure this is the case, see if you can log in here:
commerce.microsoft.com

That should tell you if you have an outstanding balance due and if so will need to contact phone support to have it sorted:
support.xbox.com/contact-us