You can send request to PayU Rest API with this library;
Example;
<?php
require_once '../vendor/autoload.php';
$merchant = new \PayuTools\Merchant('OPU_TEST', 'SECRET_KEY');
$client = new \PayuTools\Client($merchant);
$cancelRequest = new \PayuTools\Request\Token\CancelRequest('5213b33bad3c07e87e8f032c94452bdc', 'Token cancelled');
$response = $client->send($cancelRequest);
var_dump($response->getStatus());
var_dump($response->getError());
var_dump($response->getData());
?>