PPL-170 , Delete Invoice version 2 api added.

samples/rest/invoice_v2/DeleteInvoice.php

@@ -0,0 +1,23 @@
+<?php
+
+use angelleye\PayPal\rest\invoice\InvoiceAPIv2;
+
+// Include required library files.
+require_once('../../../autoload.php');
+require_once('../../../includes/config.php');
+
+$configArray = array(
+    'Sandbox' => $sandbox,
+    'ClientID' => $rest_client_id,
+    'ClientSecret' => $rest_client_secret,
+    'LogResults' => $log_results, 
+    'LogPath' => $log_path,
+    'LogLevel' => $log_level  
+);
+$PayPal = new InvoiceAPIv2($configArray);
+
+$InvoiceID = 'INV2-YZZF-D7VN-P2YM-9ZH2';    // Required.  The ID of the invoice for which to show details.
+
+$returnArray = $PayPal->DeleteInvoice($InvoiceID);
+echo "<pre>";
+print_r($returnArray);