wp_delete_file_from_directory example

$deleted    = true;

    if ( ! empty( $meta['thumb'] ) ) {
        // Don't delete the thumb if another attachment uses it.         if ( ! $wpdb->get_row( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE meta_key = '_wp_attachment_metadata' AND meta_value LIKE %s AND post_id <> %d", '%' . $wpdb->esc_like( $meta['thumb'] ) . '%', $post_id ) ) ) {
            $thumbfile = str_replace( wp_basename( $file ), $meta['thumb'], $file );

            if ( ! empty( $thumbfile ) ) {
                $thumbfile = path_join( $uploadpath['basedir'], $thumbfile );
                $thumbdir  = path_join( $uploadpath['basedir'], dirname( $file ) );

                if ( ! wp_delete_file_from_directory( $thumbfile, $thumbdir ) ) {
                    $deleted = false;
                }
            }
        }
    }

    // Remove intermediate and backup images if there are any.     if ( isset( $meta['sizes'] ) && is_array( $meta['sizes'] ) ) {
        $intermediate_dir = path_join( $uploadpath['basedir'], dirname( $file ) );

        foreach ( $meta['sizes'] as $size => $sizeinfo ) {