delete.php

<?php
require 'database.php';

if ( !isset($_GET['id']) ) {
  echo 'Please specify the id of the user to be deleted!';
  die();
}

$query = 'DELETE FROM `user` WHERE id = :id';

$statement = $pdo->prepare($query);
//bind the id of the record to be deleted
//use "i" letter for integer
$statement->bind_param(":id", $_GET['id']);

//execute delete statement
$statement->excute();
//close the prepared statement
$statement->close();

//redirect to index page
//parameter used to tell once data been deleted
header('Location:index.php? action=delete');