delete database user

<?php
$cookie_name = "loggedin";
if (isset($_COOKIE[$cookie_name])) {
	$cookie_value = $_COOKIE[$cookie_name];
}

$servername = "";
$username = "";
$password = "";
$database = "";

$conn = mysqli_connect($servername, $username, $password, $database);

if (!$conn) {
	die("Database connection failed: ".mysqli_connect_error());
}

$sql = "DELETE FROM users WHERE username='$cookie_value'";

if ($conn->query($sql) === TRUE) {
	header("Location: logout.php");
}
else {
	echo "Error deleting account: ".$conn->error;
}

?>