Remove widgets from being displayed in Page Builder

Hi,

I found this post on wordpress.org, and I need some help to understand it:
https://wordpress.org/support/topic/hiding-specific-widgets

Quote:
You can remove any widgets from being displayed in Page Builder by using the filter.

function mytheme_panels_widgets( $widgets ){
	unset($widgets['The_Widget_Class']);
	return $widgets;
}
add_filter( 'siteorigin_panels_widgets', 'mytheme_panels_widgets', 11);

You can use this to remove any widgets you need to. The example I gave runs with priority 11, to ensure it runs after all of Page Builders functions.
Quote end.

My question is:
How do I find The_Widget_Class from the different widgets?