How to Hide Document Repository Admin Menus

function plt_hide_document_repository_menus() {
	//Hide "Documents".
	remove_menu_page('edit.php?post_type=umw_document');
	//Hide "Documents → Documents".
	remove_submenu_page('edit.php?post_type=umw_document', 'edit.php?post_type=umw_document');
	//Hide "Documents → Add New Document".
	remove_submenu_page('edit.php?post_type=umw_document', 'post-new.php?post_type=umw_document');
	//Hide "Documents → Tags".
	remove_submenu_page('edit.php?post_type=umw_document', 'edit-tags.php?taxonomy=post_tag&post_type=umw_document');
}

add_action('admin_menu', 'plt_hide_document_repository_menus', 21);

Where do I put this code?