How to handle this code into codeigniter?

Code:
&lt;?php



/*Check Box Commands*/

$id=$row_notification['user_id'];



if(isset($_POST['Delete'])) {

$checkbox = $_POST['checkbox'];

mysql_select_db($database_connection_ched, $connection_ched);

$id=$row_notification['user_id'];



for($i=0;$i<count($checkbox);$i++)

  {

   $delete = "DELETE FROM tb_user WHERE user_id=$checkbox[$i]";

   mysql_query($delete,$connection_ched);

   

  }

$result2 = mysql_query($delete);



 if($result2)

 {

 echo "[removed]alert ('Successfully Deleted');[removed]"; 

 echo "&lt;meta http-equiv=\"refresh\" content=\"0;URL=notification.php?\"&gt;"; }

 

}



/*End of Checkbox Commands*/

?&gt;