PHP SOLUTIONS

Put this code at templet/checkout/cart/item/default.phtml
at line 26 or 27
after this line "$_item = $this->getItem();"

<?php

echo $temp = $_item->getProductId();
echo "<br/>";
$_product = Mage::getModel('catalog/product')->load($temp);
echo "Config. Product :";
echo $_product->getSku();
echo "<br/>";

echo "Simple Product :";
echo $_item->getSku();

?>

<?php
$session= Mage::getSingleton('checkout/session');
$quote = $session->getQuote();

$cart = Mage::getModel('checkout/cart');
$cartItems = $cart->getItems();
foreach ($cartItems as $item)
{
    if($item->getProductId()== 4)
    {
        $quote->removeItem($item->getId())->save();
    }
}

<?php
            
            $cart = Mage::getSingleton('checkout/cart');
$product = new Mage_Catalog_Model_Product();
$product->load(4);

$cart->addProduct($product);
$cart->save();

?>

Write This in "templet/checkout/cart/item/default.phtml"
<?php

$_item = $this->getItem();

echo $temp = $_item->getProductId();
echo "<br/>";
$_product = Mage::getModel('catalog/product')->load($temp);
echo "Config. Product :";
echo $_product->getSku();
echo "<br/>";

echo "Simple Product :";
echo $_item->getSku();