add_action('bp_ajax_querystring','bpdev_exclude_users',20,2);
function bpdev_exclude_users($qs=false,$object=false){
    //list of users to exclude
   
    $excluded_user='1,2,3';//comma separated ids of users whom you want to exclude
   
    if($object!='members')//hide for members only
        return $qs;
    
    $args=wp_parse_args($qs);
    
    //check if we are searching for friends list etc?, do not exclude in this case
    if(!empty($args['user_id'])||!empty($args['search_terms']))
        return $qs;
    
    if(!empty($args['exclude']))
        $args['exclude']=$args['exclude'].','.$excluded_user;
    else 
        $args['exclude']=$excluded_user;
      
    $qs=build_query($args);
   
   
   return $qs;
    
}