Magento 2 how to remove customer previously added product from cart

Question

Steps :

1. When I add any product to cart and go to the checkout page.
2. On the checkout page when I login with customer who added product previously then the product will be added to the cart.

I want to stop or remove this functionality so what steps should I follow.

Answer 1

You may create an event to delete existing quote items when merging quotes. Somewhat like below.

etc/events.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_quote_merge_before">
        <observer name="remove_old_quote_items" instance="Vendor\Module\Observer\RemoveOldQuoteItems" />
    </event>
</config>

Observer/RemoveOldQuoteItems.php

<?php

namespace Vendor\Module\Observer;

use Magento\Framework\Event\ObserverInterface;

class RemoveOldQuoteItems implements ObserverInterface
{
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        if ($observer->getQuote()->getAllVisibleItems()) {
            foreach ($observer->getQuote()->getAllVisibleItems() as $item) {
                $observer->getQuote()->removeItem($item->getId())->save();
            }
        }

        return $this;
    }
}