$sql="DELETE FROM request WHERE reqNr='".$deleteReq."'";

<?php
    $host="localhost"; // Host name
    $username="test"; // Mysql username
    $password="test"; // Mysql password
    $db_name="test"; // Database name



    mysql_connect("$host", "$username", "$password")or die("cannot connect");
    mysql_select_db("$db_name")or die("cannot select DB");

   $deleteReq = $_POST['reqNr2'] ;

    $sql="DELETE FROM request WHERE reqNr='$deleteReq'";
    $result=mysql_query($sql);

    if ($result)
    {
        echo "Deleted Successfully ReqNr: ".$deleteReq;
        echo "<br>";

    }
    else
    {
        echo "ERROR!";
        // close connection
        mysql_close();
    }
?>