A while ago I made a Firefox account with my Yahoo email address as the primary email, and my Outlook email address as the secondary email. Eventually I realized that I didn't need my Yahoo email account anymore, so I deleted it, forgetting that it was being used as the primary email for my Firefox account. Now I can't remove my Outlook email from my Firefox account without verifying my Yahoo email account, and I can't even delete the Firefox account since it was made under the Yahoo email account as a primary email address.

Now I can't use my Outlook email address to create a new Firefox account either.