Tips on Customizing Seraphinite Alternative Slugs Manager

How to Hide the "Alternative Slugs" Admin Menu

function plt_hide_seraphinite_old_slugs_mgr_menus() {
	//Hide the "Settings → Alternative Slugs" menu.
	remove_submenu_page('options-general.php', 'seraph_osm_settings');
}

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

Where do I put this code?

How to Hide the "Slug: Alternatives" Meta Box

function plt_hide_seraphinite_old_slugs_mgr_metaboxes() {
	$screen = get_current_screen();
	if ( !$screen ) {
		return;
	}

	//Hide the "Slug: Alternatives" meta box.
	remove_meta_box('seraph_osm_editor', $screen->id, 'normal');
}

add_action('add_meta_boxes', 'plt_hide_seraphinite_old_slugs_mgr_metaboxes', 20);