Magento 2: Remove discount applied(Coupon code applied) on place order event

Question

I want to remove discount applied(Coupon code applied) when order is placed. Any help would be appreciated.

My controller code:

class Success extends \Magento\Checkout\Controller\Onepage implements HttpGetActionInterface
{
    /**
     * Order success action
     *
     * @return \Magento\Framework\Controller\ResultInterface
     */
    public function execute()
    {
        $session = $this->getOnepage()->getCheckout();

        if (!$this->_objectManager->get(\Magento\Checkout\Model\Session\SuccessValidator::class)->isValid()) {
            return $this->resultRedirectFactory->create()->setPath('checkout/cart');
        }
        $session->clearQuote();


        //@todo: Refactor it to match CQRS
        $resultPage = $this->resultPageFactory->create();
        $this->_eventManager->dispatch(
            'checkout_onepage_controller_success_action',
            [
                'order_ids' => [$session->getLastOrderId()],
                'order' => $session->getLastRealOrder()
            ]
        );
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
        $checkoutSession = $objectManager->get('\Magento\Checkout\Model\Session');
        $checkoutSession->getQuote()->setCouponCode('NEW10')->collectTotals()->save();

        return $resultPage;
    }
}

Answer 1

In your case, do this things :

$checkoutSession->getQuote()->setCouponCode('')->collectTotals()->save();

Answer 2

Create a Custom Module Vendor_ModuleName and add the Following Files :

app/code/Vendor/ModuleName/etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <type name="Magento\SalesRule\Model\RulesApplier">
        <plugin name="remove_coupon_on_order" type="Vendor\ModuleName\Plugin\SalesRule\Model\RulesApplier" sortOrder="1" disabled="false"/>
    </type>
</config>

app\code\Vendor\ModuleName\Plugin\SalesRule\Model\RulesApplier.php

<?php
 
namespace Vendor\ModuleName\Plugin\SalesRule\Model;
 
class RulesApplier
{
 
    private $rules;
 
    public function __construct(
        \Magento\SalesRule\Model\ResourceModel\Rule\CollectionFactory $rulesFactory
    ) {
        $this->ruleCollection = $rulesFactory;
    }
 
    public function aroundApplyRules(
        \Magento\SalesRule\Model\RulesApplier $subject,
        \Closure $proceed,
        $item,
        $rules,
        $skipValidation,
        $couponCode
    ) {
        $rules = $this->ruleCollection->create()->addFieldToFilter("rule_id", ["eq"=> ""]);
        $result = $proceed($item, $rules, $skipValidation, $couponCode);
        return $result;
    }
}

Hope It Will Help You !!