How to Hide the "GRIT Taxonomy Filter" Admin Menu

function plt_hide_grit_taxonomy_filter_menus() {
	//Hide the "Settings → GRIT Taxonomy Filter" menu.
	remove_submenu_page('options-general.php', 'grit_taxonomy_filter');
}

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

Where do I put this code?