When trying to register I first attempted using github for authentication, but this failed as I didn’t have 2FA turned on. I don’t want to set that up at this point, but there was no obvious way to switch providers or set up with an email address. Clearing cookies for discourse.mozilla.org and reopening the browser didn’t work. In the end I signed up by browsing to the site in private window mode.
I have the same issue. Tried resetting cookies for almost everything having “moz” it its name/domain + auth0.com, but nothing helps, it still remembers the github.
If you cannot access SSO Dashboard for the same reasons, there is another way. When the Auth0 page is open, stop loading the page, so that it doesn’t redirect you, open up the Developer Tools and enter this in the Console:
localStorage.removeItem( ‘nlx-last-used-connection’ )