/**
 * Apply weight-based shipping options in the checkout process
 */

add_filter('woocommerce_package_rates', 'cc_weight_based_shipping_options', 9999, 2);

function cc_weight_based_shipping_options($rates, $package) {

  if (WC()->cart->get_cart_contents_weight() > 2000) {

    unset($rates['flat_rate:4'], $rates['flat_rate:5']);

  }

  return $rates;

}