Hi!
In this case, you need to write a simple module.
1) Create a module according to
http://kb.x-cart.com/display/XDD/How+to+create+a+module
2) In your Main.php file create the runBuildCacheHandler method as described here:
http://kb.x-cart.com/pages/viewpage.action?pageId=7504837#Webinar2-10Apr2014-DesignchangesinX-Cart5(Custom...-2.2.ByPHPcode
You runBuildCacheHandler will look like this:
PHP Code:
public static function runBuildCacheHandler()
{
parent::runBuildCacheHandler();
\XLite\Core\Layout::getInstance()->removeTemplateFromLists('order/invoice/parts/bottom.tpl');
}