Automatically hide OpenGraph meta box from post creation page

The Ultimate Facebook plugins creates two meta boxes on my admin panel: OpenGraph Settings and Facebook Publishing. However, for new users I want to hide these settings by default.

I tried doing the following:

function eliminar_cajas_meta(){
	remove_meta_box( 'postcustom',               'tarea', 'normal' );
	remove_meta_box( 'sharing_meta',             'tarea', 'normal' );
	remove_meta_box( 'slugdiv',                  'tarea', 'normal' );
	remove_meta_box( 'wdfb_facebook_publishing', 'tarea', 'normal' );
	remove_meta_box( 'wdfb_opengraph_editor',    'tarea', 'normal' );
}
add_action('add_meta_boxes', 'eliminar_cajas_meta');

All the other meta boxes end up hidden, but the Facebook related ones remain in the interface.

I wonder how can they be hidden if the remove_meta_box command does not seem to work on them.

Kind regards,
Carlos.