Snippet to hide price on WooCommerce products in selected category.

Hide WooCommerce Product Price

/**** Custom Code to hide product prices based on the associatin with specific categories. ****/
/**** Place the following code at the bottom of theme's functions.php file. ****/

/**
 * Remove price on product detail page
 *
 * @param none
 * @return none 
 */
function remove_prices_based_on_category() {

  // If its a product detail page.  
  if ( is_product() ) {
    remove_product_price( get_the_ID() );
  }

}
add_action( 'wp', 'remove_prices_based_on_category' );

/**
 * To remove price of a product by product id.
 *
 * @param $product_id
 * @return none 
 */
function remove_product_price( $product_id ) {
    $product_id  = get_the_ID();
    $hidden_price_category_ids = array( '27419','27421' ); // Add Product Category IDs for which the product price should be hidden.
    $product_cat_ids  = get_the_terms( $product_id, 'product_cat' ); // Getting all categories for this product.
    $cat_ids = wp_list_pluck( $product_cat_ids, 'term_id' ); // Getting all category ids for this product.   
    $result = array_intersect( $hidden_price_category_ids, $cat_ids ); // Will match hidden price categories with product categories and the cat id in the array.
    
    // If a hidden pice category is found
    if( !empty($result) ) {
        add_filter( 'woocommerce_get_price_html', 'return_custom_price', 10, 2 );
        remove_action( 'woocommerce_single_product_summary', 'woocommerce_template_single_add_to_cart', 30 );
        remove_action( 'woocommerce_after_shop_loop_item', 'woocommerce_template_loop_add_to_cart' );
    } else {
        remove_filter( 'woocommerce_get_price_html', 'return_custom_price', 10, 2 );
        add_action( 'woocommerce_single_product_summary', 'woocommerce_template_single_add_to_cart', 30 );
        add_action( 'woocommerce_after_shop_loop_item', 'woocommerce_template_loop_add_to_cart' );
    }
}
add_action( 'woocommerce_before_shop_loop_item', 'remove_product_price', 5, 1 ); // for each product on product listing page/shop page.

/**
 * To remove price of a product by product id.
 *
 * @param $price price html
 * @return string price html
 */
function return_custom_price( $price, $instance ) {
    $price = '<span style="color:red; font-size:12px;">Call our office <strong>516.695.3110</strong> for prices.</span>';
    return $price; 
}