Hide default Widgets

Hello,

I am new with the SiteOrigin PageBuilder. I want to hide default Widgets like Navigation, Meta, Search, … so I found this snippet:

function mytheme_remove_widgets($widgets){
    unset($widgets['Unwanted_Widget_Class']);
    return $widgets;
}
add_filter('siteorigin_panels_widgets', 'mytheme_remove_widgets');

But I can’t figure out what the class names of the default widgets are. I looked into the plugins/siteorigin-panels/widgets/widgets folder, but there are only a few widgets.

So how can I remove default widgets like Navigation, Meta, Search?