Magento 2 Programatically clear all tax and Add custom in Observer

Question

I am customize tax calculation on and adding custom tax.I am doing this using observer:

Magento Version is 2.3.4 ,below code is working fine and adding custom rates but My requirement to add clear all added tax before adding new one.

<?xml version="1.0" encoding="UTF-8"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_quote_address_collect_totals_after">
        <observer name="changeTaxTotal" instance="Vendor\CustomTax\Observer\ChangeTaxTotal"/>
    </event>
</config>

and observer file is

<?php

namespace Vendorname\CustomTax\Observer;

use \Magento\Framework\Event\ObserverInterface;
use \Magento\Framework\Event\Observer;

class ChangeTaxTotal implements ObserverInterface
{
   
    public function execute(Observer $observer)
    {
        
        /** @var Magento\Quote\Model\Quote\Address\Total */
        $total = $observer->getData('total');
        
        $subtotal = $total['subtotal'];
        $customTax = ($subtotal * 9)/100;
        
        if (trim($total['shipping_description']) == "Shipping_methode_name") {
           ------------in this line I want to clear all tax -------
            $total->addTotalAmount('tax', $customTax);
        }
       
        return $this;
    }
}

I want to Clear all added tax before adding my custom rateand also want to add tax title. $total->addTotalAmount('tax', $customTax);

If anyone have idea please share me.

Answer 1

Please change the code as below and try

From:

if (trim($total['shipping_description']) == "Shipping_methode_name") {
           ------------in this line I want to clear all tax -------
            $total->addTotalAmount('tax', $customTax);
        }

To:

if (trim($total['shipping_description']) == "Shipping_methode_name") {
           ------------in this line I want to clear all tax -------
            $total->setTotalAmount('tax', $customTax);
        }

Answer 2

Please use below code for change title

if (trim($total['shipping_description']) == "Shipping_methode_name") {
           ------------in this line I want to clear all tax -------
            $total->setTotalAmount('tax', $customTax);
            $infos = $total->getFullInfo();
            foreach($infos as $key1 => $info) {
               foreach($info['rates'] as $key2 => $rate) {
                  if($rate == 'Tax') {
                     $infos[$key1]['rates'][$key2]['title'] = 'YOUR CUSTOM TITLE';
                  }
               }
            }
            $total->setFullInfo($infos);
        }