Set region id null on checkout

I’m trying to save region id as a null value after clicking next from shipping tab to the payment tab on the checkout page.
I have used the below file to setRegionId() which is working fine if I add integers from 1 and above but if I update null or 0 it’s not getting updated in the quote_address table.

MagentoCheckoutModelShippingInformationManagement::saveAddressInformation

$shippingAddress = $quote->getShippingAddress();
$shippingAddress->setData("region_id",null);

Also, I tried this one below

$shippingAddress->setRegionId(null);

Both are not working. I just want to update region_id null in the quote_address table when a customer clicks next and goes to the payment page.