delete product from cart not working in prestashop

[NishantVadgama]

I am using prestashop 1.6.0.14

and In my local store I have overrided paymentModule's validation() method and in that method I have check that if cart having product id = 18 then remove it.

code as follows

 

if ($this->context->cart->containsProduct(18))

{

$this->context->cart->deleteProduct(18);

this->context->cart->update();

}

it works fine remove product from ps_cart_product table but order placed with that product why so..?

to trace I have printed as follows

 

if ($this->context->cart->containsProduct(18))

{

$this->context->cart->deleteProduct(18);

this->context->cart->update();

print_r('<br>---------------------------------------------------------<br>');

print_r($this->context->cart->getProducts());

print_r('<br>---------------------------------------------------------<br>');

print_r($this->context->cart->getPackageList());exit;

}

when print getProducts() does not contain product id 18 but getPackageList() still contains that product why so..?

and how can I delete product form that also..?

help me please