update-checkout.js

/**
** After update checkout
**/
$(document.body).on('update_checkout, updated_checkout', function () {
  validate_checkout_required_fields();
});

function validate_checkout_required_fields() {
  if($('select.shipping_method').val() == "wc_pickup_store") {
    $('#billing_state_field, #billing_city_field, #billing_address_1_field').find(".required").hide();
    $('#billing_state_field, #billing_city_field, #billing_address_1_field').removeClass("validate-required woocommerce-validated woocommerce-invalid woocommerce-invalid-required-field");
  } else {
    if($('#billing_state_field .required, #billing_city_field .required, #billing_address_1_field .required').length < 1) {
      $('#billing_state_field label, #billing_city_field label, #billing_address_1_field label').append('<abbr class="required" title="obligatorio">*</abbr>');
    } else {
      $('#billing_state_field, #billing_city_field, #billing_address_1_field').find(".required").show();
    }
    $('#billing_state_field, #billing_city_field, #billing_address_1_field').addClass("validate-required");
  }
}