[Theme: Pink Touch 2] Working with a little modification

You need to add this code at the bottom of functions.php

function is_multi_author() {
  global $wpdb;
  $rows = (array) $wpdb->get_col("SELECT DISTINCT post_author FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' LIMIT 2");
  $is_multi_author = 1 < count( $rows ) ? 1 : 0;
  return (bool) $is_multi_author;
}

https://www.ads-software.com/extend/themes/pink-touch-2/