Why have you dropped the $_POST superglobal variable assignments? That's how the data is passed from the function. Also, the mysql_real_escape_string() should be after a mysql connection.
PHP Code:
<?php
$db_host = <defined>
$db_user = <defined>
$db_pwd = <defined>
$database = <defined>
$table =<defined>
if (!mysql_connect($db_host, $db_user, $db_pwd))
die("Can't connect to database");
if (!mysql_select_db($database))
die("Can't select database");
$tval = mysql_real_escape_string($_POST['tval']);
$cval = mysql_real_escape_string($_POST['cval']);
$sql = mysql_query("DELETE FROM expedia WHERE `tag`='$tval' AND `cpm`=$cval" );
if (!$sql) {
die(mysql_error());
}
mysql_free_result($result);
?>