Make VAT field not required

WooCommerce B2B, among its features, adds VAT number field in checkout page form and in registration form (if “Extended registration form” option is enabled).
This field is mandatory, as required in most B2B stores.
But in some cases, you may want the VAT field to be optional, such as in stores that have both B2B and B2C.

To do this, edit functions.php file that you find in your site’s FTP space in:

 wp-content/themes/{YOUR_ACTIVE_THEME}/functions.php

and insert this code:

add_filter( 'woocommerce_billing_fields' , function( $fields ) {
    $fields['billing_vat']['required'] = false;
    return $fields;
} );