The regex uses / as the delimiter when searching for / you escape it like so \/ see example test code <?php
$TEMPLATE_PATH ="c://test//example/////test.php";
print $TEMPLATE_PATH;
$TEMPLATE_PATH = ereg_replace("(/)+" ,"/",$TEMPLATE_PATH); //----Deprecated
$TEMPLATE_PATH = preg_replace('/(\/)+/', '/', $TEMPLATE_PATH);
print $TEMPLATE_PATH;
?>