What account are you talking about?

If you have deleted the email address that was used for the Firefox Account (Sync) and you can no longer access this Sync account then you will have to create a new account for Sync.

In case of issues try to log in to the Firefox Account via this website to delete the acount.

• https://accounts.firefox.com/signin

See also:

• https://support.mozilla.org/en-US/kb/ive-lost-my-firefox-sync-account-information
• https://support.mozilla.org/en-US/kb/change-primary-email-address-firefox-accounts

I had an account demaere.c@unseen.is

What happens if you try to login to this account?

• https://accounts.firefox.com/signin

If you need to answer a confirmation email then there is no way to access this account and you need to create a new account with a valid email address.

Ok, I can't remember the password so looks like I'm unable to delete it.