Udało się zrobić.
Trzeba usunąć:
function hookHeader($params)
{
global $smarty,$cookie;
if(_PS_VERSION_ > "1.4.0.0" && _PS_VERSION_ < "1.5.0.0"){
Tools::addCSS(__PS_BASE_URI__.'css/jquery.jgrowl.css', 'all');
Tools::addJS(__PS_BASE_URI__.'js/jquery/jquery.jgrowl-1.2.1.min.js');
}
if(_PS_VERSION_> "1.5..0")
{
$this->context->controller->addCSS(__PS_BASE_URI__.'css/jquery.jgrowl.css', 'all');
$this->context->controller->addJS(__PS_BASE_URI__.'js/jquery/jquery.jgrowl-1.2.1.min.js');
}
return $this->display(__FILE__, 'hidepricecart-header.tpl');
}