woocommerce_get_price_html.php

<?php
/**
 * Hide products with specific IDs
 * Edit line 7 with the IDs you want to hide prices for
 */
add_filter( ‘woocommerce_get_price_html’, function( $price, $product ) {
  if( is_admin() ) return $price;
  $product_ids = array( 1234, 5678 );
  if( in_array( $product->get_id(), $product_ids ) ) {
    return '';
  }
  return $price;
});