To hide Admin user from another users just copy below code and paste in your active theme functions.php file.

Replace the <USERNAME OF ADMIN> text with the actual usernames of the users involved. You can also modify this to hide one admin from all other users (except him/herself), or based on user IDs or roles. For WordPress 3.1+.

function sangvish_pre_user_query($user_search) {
  global $current_user;
  $username = $current_user->user_login;

  if ($username == '<USERNAME OF ADMIN>') { 
    global $wpdb;
    $user_search->query_where = str_replace('WHERE 1=1',
      "WHERE 1=1 AND {$wpdb->users}.user_login != '<YOUR USERNAME>'",$user_search->query_where);