Clearing Cart

I just realized when I try to clear my cart (which is a cookie based cart), I am an error at the top of the cart.php page that says "BBKD0G9
Warning: Cannot modify header information - headers already sent by (output started at /home/content/05/11651305/html/1to1-silpada/cart.php:147) in /home/content/05/11651305/html/1to1-silpada/WA_eCart/eCart1_PHP.php on line 190"

Line 190 is part of the function below How do I fix this? I am including the pages and credentials privately.

function SetCookieInfo($theCookieString) {
$numDays = 14;
$theDomain = "";
$thePath = "";
$cookSec = false;
if ($numDays == "") $numDays="0";
$theDate = strtotime("+".$numDays." Days");
setcookie($this->CartName."_Items", $theCookieString, $theDate, $thePath, $theDomain, $cookSec);
}