<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Planner\Tasks\Item\PlannerTaskItemRequestBuilderDeleteRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new PlannerTaskItemRequestBuilderDeleteRequestConfiguration();
$headers = [
'If-Match' => 'W/"JzEtVGFzayAgQEBAQEBAQEBAQEBAQEBAWCc="',
];
$requestConfiguration->headers = $headers;
$graphServiceClient->planner()->tasks()->byPlannerTaskId('plannerTask-id')->delete($requestConfiguration)->wait();