filter to remove select countries where the VAT number field will show for

wc-eu-vat-remove-some-countries.php

add_filter( 'woocommerce_eu_vat_number_country_codes', 'woo_custom_eu_vat_number_country_codes' );
function woo_custom_eu_vat_number_country_codes( $vat_countries ) {
    $display_vat = array_diff($vat_countries, ['SE', 'GB']); // remove countries in second array
    return array_values($display_vat); // reindex array
}

Thank you to @robman87 for the original - https://gist.github.com/rynaldos-zz/edeb6c82904267d19538f1e49ce26894#gistcomment-3590910