title: Firebase Auth saved after uninstall. How can I delete it?
body: <p>I've recently discovered that Firebase Auth saves itself on the device even after my app is uninstalled. I can't figure out how to REMOVE this old Auth info.</p>
  
  <p>I don't want a user to still be signed in after uninstalling and reinstalling the app. If for no other reason than my own testing of what I expect to be "clean installs" on the same device.</p>
  
  <p>I understand there is no easy way to capture an uninstall event, so I want to clear out any potential old Auth info on the first launch.</p>
  
  <p>So I added code (which seems to work fine) to check if this is the first launch:</p>
  
  <pre><code>Boolean firstRun = prefs.getBoolean("firstrun", true);
  if (firstRun) {
      // delete everything an old user could have left behind
      // ==&gt; This is where I need help &lt;==
      prefs.edit().putBoolean("firstrun", false).apply();
  } else {
      // move along, not the first launch
  }
  </code></pre>
  
  <p>I've tried (unsuccessfully): </p>
  
  <pre><code>FirebaseAuth authData = FirebaseAuth.getInstance();  
  authData.signOut();
  </code></pre>
  
  <p>These calls also seem to be the advice in this related question for iOS, but I haven't been able to apply its wisdom:
  <a href="https://stackoverflow.com/questions/27893418/firebase-deleting-and-reinstalling-app-does-not-un-authenticate-a-user?utm_medium=organic&amp;utm_source=google_rich_qa&amp;utm_campaign=google_rich_qa">Firebase - Deleting and reinstalling app does not un-authenticate a user</a></p>
  
  <p>Even after calling <code>signOut()</code> the app keeps logging me in under the old account!</p>
  
  <p>My "logout" button uses <code>FirebaseAuth.getInstance().signOut();</code> and works. <strong>Is there something odd (possessed?) about this "old" Auth instance that is being saved after an uninstall that it just won't die</strong>? </p>
  
  <p>Specifically when I uninstall and then install/run from Android Studio: </p>
  
  <ol>
  <li>at first authData and currentUser both are not null</li>
  <li>I call the above code, trying to get rid of this old user</li>
  <li>3 millisecond later (immediately after I call that
  code) they are still NOT NULL.</li>
  <li>Another 2 milliseconds, currentUser IS NULL (yay?)</li>
  <li>Another 71 milliseconds... still null (so far so good)</li>
  <li>Just under a second later... I'M SIGNED IN AS THE OLD USER?! How is this possible?</li>
  </ol>
  
  <p>In the Firebase Console under Authentication, this account is shown as last signed in 6 days ago. So it's not somehow getting re-signed-in.</p>
  
  <p><strong>Does anyone know how to remove FirebaseAuth data from a device? I don't want to "delete" the user account, just remove all traces of it from this device.</strong></p>
  
  <p>Oddly enough, the account I keep getting unwillfully logged in under isn't even the last account that logged into my app on this device. And this was never a problem in the past (hence my not even knowing that Firebase saved Auth after uninstall). So it looks like Auth info isn't <strong>always</strong> saved after uninstall... but when it happens it's impossible to remove?</p>
  
  <p>Any help much appreciated! </p>