title: Firebase: How to always force a sign-in?
body: <p>Working in Eclipse, &amp; using the <a href="https://github.com/firebase/quickstart-js/tree/master/auth" rel="noreferrer">provided methods</a> in Firebase' docs, I was able to setup logins for several providers such as Google and Facebook, using the redirect option. I basically click on a button for the provider on my web page, &amp; it takes me to the login screen where I can enter a UID and password (e.g. Google sign-in)</p>
  
  <p>However, once I authenticate properly with a valid account, and even if I sign-out, I get logged into the same account, without ever getting the screen prompting to log in. Where is this information persisted? Closing out Eclipse, or turning the computer off, does nothing to help, so I believe this is all being saved somewhere.</p>
  
  <p>How do I "forget" previous attempts, so that I can see a provider's log in screen, each and every time?</p>