Php erreur redirection

<?php
session_start(); //demarre la session
if(!isset($auth)){
if(!isset($_SESSION['Auth']['id'])){
	header('Location:' . WEBROOT. 'login.php'); //redirection
	die();
	}
}


if(!isset($_SESSION['csrf'])){
	$_SESSION['csrf'] = md5(time() + rand ());

}

function csrf(){
	return 'csrf=' . $_SESSION['csrf'];


}

function checkCsrf(){
	if(!isset($_GET['csrf']) OR $_GET['csrf'] != $_SESSION['csrf']){
		header('Location:' . WEBROOT . '/csrf.php');
		die();
	}
}

?>

<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<?php
include '../lib/includes.php';
include '../partials/admin_header.php';


$select = $db->query('SELECT id, name, slug FROM categories');
$categories = $select->fetchAll();

// SUPPRESSION
if(isset($_GET['delete'])){
	checkCsrf();
}
?>


<h1>Les catégories</h1>


<table class="tablet table-striped">
	<thead>
		<tr>
			<th>Id</th>
			<th>Nom</th>
			<th>Actions</th>
		</tr>
	</thead>
	<tbody>
		<?php foreach ($categories as $category) : ?>
			<tr>
			<td><?php echo $category['id'];?></td>
			<td><?php echo $category['name'];?></td>
			<td>

				<a href="category_edit.php?id=<?php echo $category['id'];?>" class="btn btn-default">Edit</a>
				<a href="?delete=<?php echo $category['id']; ?>" class="btn btn-error" onclick="return confirm('Sur vraiment sur ?');">Supprimer</a>
			</td>
		</tr>

			<?php endforeach; ?>
			</tbody>

</table>

<?php 
include '../partials/footer.php';
?>