Hey there, unfortunately there is only really one thing you can do - as of March 2025 it is no longer possible to unlink platform accounts, as you mention, meaning even if you could authenticate it, you still can't remove it. Bungie will never adjust anyone's link or cross-save settings on their end under any circumstances and are not offering exceptions to the unlink policy. So the only avenue is that it's still possible to recover the XBox account even without access to the original email. The recovery process asks for a working email, this is not the original email, just what they can use to contact you with. You'll then fill out a form with as much info as possible to help them identify your account and let you regain access.