Alternative Of PHP

I have got the following PHP code which I am trying to convert to
ASP.cant find a replace function for Unset in asp which will discard the variable
if ($categoryid == "all")
{
$sql = "SELECT * FROM products where shopinspection=$shopinspection";
unset($HTTP_POST_VARS['categoryid']);
unset($HTTP_POST_VARS['shopinspection']);
}
else
{
$sql = "SELECT * FROM products where categoryid = $categoryid";
unset($HTTP_POST_VARS['categoryid']);
}
unset($HTTP_POST_VARS['Submit']);
while (list($key, $value) = each($HTTP_POST_VARS))
{
if ($value != "" )
{
$sql = $sql .=" AND $key=$value";
//$sql = $sql .=" AND solesource = $solesource";
//echo "<strong>$value</strong>";