Before start it, please understand I’m newbie

I coded it

    public void Start()
    {
        UserInformationRenewal();
    }

    public void UserInformationRenewal()
    {
        FirebaseDatabase.DefaultInstance.RootReference
            .Child("users")
            .Child(firebaseLogin.userId)
            .Child("received")
            .ValueChanged += HandleValueChanged;
    }

    public void UserInformationReset()
    {
        FirebaseDatabase.DefaultInstance.RootReference
            .Child("users")
            .Child(firebaseLogin.userId)
            .Child("received")
            .ValueChanged -= HandleValueChanged;
    }

    void HandleValueChanged(object sender, ValueChangedEventArgs args)
    {
        print("changed");
        if ((bool)args.Snapshot.Value == true) SocialNotification(true);
        else if ((bool)args.Snapshot.Value == false) SocialNotification(false);
    }

and UserInformationReset() doesn’t work
(firebaseLogin.userId is “FirebaseAuth.DefaultInstance.CurrentUser.UserId;” and it works well)

I tried print(“success”) in UserInformationReset(), it printed “success” successfully but ValueChange event has not removed
and tried

    public void UserInformationReset()
    {
        FirebaseDatabase.DefaultInstance.RootReference
            .Child("users")
            .Child(firebaseLogin.userId)
            .Child("received")
            .SetValueAsync("test");
    }

then, “test” value set in “reveiced” successfully in Firebase Realtime Database

there’s no error message