while (NavigationService.CanGoForward) NavigationService.RemoveBackEntry();

Window mainWindow = Application.Current.MainWindow;
        Frame _frame = (Frame)mainWindow.FindName("mainFrame");
        foreach (JournalEntry j in _frame.ForwardStack)
        {
            MessageBox.Show(j.Name);
        }

void Frame_Navigating(object sender, NavigatingCancelEventArgs e)
    {
        bool b = e.NavigationMode == NavigationMode.Forward;
        if (b)
        {

            e.Cancel = true;
        }
    }