Delete files from directory

[eluser]Zeeshan Rasool[/eluser]
Hi, anyone here that tell me about this prob.This is function in model i want to delete uploaded video file from folder './public/videos'

$this->db->where('video_id', $video_id);
$this->db->select(trim('video_path'));
$query = $this->db->get('help_video');
foreach($query->result() as $item)
{
$old_video_path=($item->video_path);
}
delete_files('./public/videos/'.$old_video_path);
$this->db->where('video_id', $video_id);
$this->db->delete('help_video');

Problem:the information such as video title and path is deleted from DB but video file is still in directory. What shud me do!
.....thnx in Adv.