WP_Customize_Manager::settings PHP Method

    public function settings()
    {
        return $this->settings;
    }

 public function reset_customizer()
 {
     $settings = $this->wp_customize->settings();
     // remove theme_mod settings registered in customizer
     foreach ($settings as $setting) {
         if ('theme_mod' == $setting->type) {
             remove_theme_mod($setting->id);
         }
         if ('option' == $setting->type) {
             global $igthemes_option;
             delete_option($igthemes_option);
         }
     }
 }