[Solved] Any unregistered user can login (PHP)

Your code never checks if the user account exists in the database. It only checks if the query was executed without error. This should work(untested):

$query = "SELECT * FROM Users WHERE Email="$email" AND Password='$password' LIMIT 1";
if($result = mysqli_query($conn, $query)){

    if(mysqli_num_rows($result) > 0){

        //user account exists
        $member = mysqli_fetch_array($result, MYSQLI_ASSOC);
        $email = $member["Email"];

    } else {

        //user account does not exist

    }

} else {

    echo "Error executing database query.";

}