How to make a user sign out in Firebase?

Question

I am making a simple authentication app in Android using Firebase authentication. Till now I am successful in signing the user in, however the issue is that the user remains

Answer 1

FirebaseAuth.getInstance().signOut();

Then, to detect the sign-in status:

private FirebaseAuth mAuth = FirebaseAuth.getInstance()
public static boolean mAuthSignIn() {
    if (mAuth != null) {
        FirebaseUser user = mAuth.getCurrentUser();
        return user != null;
    }
    return false;
}