How to Hide the "SiteOrigin Widgets" Admin Menu

function plt_hide_so_widgets_bundle_menus() {
	//Hide the "Plugins → SiteOrigin Widgets" menu.
	remove_submenu_page('plugins.php', 'so-widgets-plugins');
}

add_action('admin_menu', 'plt_hide_so_widgets_bundle_menus', 11);

Where do I put this code?