<?php
if(!isset($_SESSION['id'])) {
    echo '<li><a href="includes/logoutsystem.php"><i class="fas fa-sign-out-alt"></i>Log Out</a></li>';
    } else {
    echo '
        <li><a href="login.php"><i class="fas fa-sign-in-alt"></i>Log In</a></li>
        <li><a href="signup.php"><i class="fas fa-user-plus"></i>Sign Up</a></li>';
    }
?>

<?php
    unset($_SESSION['id']);
    session_destroy();
    header("Location: ../index.php");
?>