Secondary account confirmation
I understand that the following is necessary as described in the FAQ. I lost my two-step authentication device, can’t find my backup authentication codes and don’t have a logged-in device. Can I request to delete my Firefox Account?
Is it possible to remove the backup account related to such a locked-out account to allow that account to be associated with the new account created?
Note that the Authy locked account has been abandoned on Firefox for a long time. Not certain if there is a limit time-frame of no account access after which the account may be declared abandoned and may therefore have the backup account unlocked for a new account association to the backup account.
Firefox forum can't do this request it's only a user help forum. You need access login with the primary email to get the reset or to change login email. Without that email account access there's nothing more that can be done here.