While using search intergrations in site, we may need to customize the search results based on the market requirement. We had a similar requirement where pages like contact us, privacy policy need to be excluded from search results page, we achieved this by using following function

function your_module_apachesolr_exclude($entity_id, $entity_type, $row, $env_id) {
  $exclude_pages = array('1' => 'contact-us', 100 => 'privacy policy');
  // Never index page not found node.
  foreach($exclude_pages as $nid => $page) {
    if ($nid == $entity_id) {
      return TRUE;
    }
  }
  return FALSE;
}

You might need to reindex the contents for changes to be reflected.