unsubscribe_noptin_subscriber( $subscriber )

function unsubscribe_noptin_subscriber( $subscriber ) {
	$subscriber = new Noptin_Subscriber( $subscriber );

	if ( $subscriber->exists() ) {

		// Deactivate the subscriber.
		deactivate_noptin_subscriber( $subscriber );

		// (maybe) delete the subscriber.
		if ( get_noptin_option( 'delete_on_unsubscribe' ) ) {
			delete_noptin_subscriber( $subscriber->id );
		}

	}

}