Doubt in the logoff in php

Question

Would anyone have any idea why even by destroying the session that stores a logged-in user on the site, when accessing url directly shown as if the user remained logged in, even after the call from session_destroy();?

index

<li class="nav-item">                       
<a class="nav-link" rel="tooltip" title="Sair" data-placement="bottom" href="pag-login.php" target="_self">

<i class="fas fa-sign-out-alt"></i>

<?php echo $_SESSION['email'];?>

// CHAMADA DO ARQUIVO QUE DESTROY AS SESSION:
<a href="sair.php"></a>

</li>  

quit php.

<?php

session_start();

unset(
    $_SESSION['email'],

    $_SESSION['id'],
    $_SESSION['tipo_user'],
    $_SESSION['nao_autenticado']);
session_destroy();

header('Location: pag-login.php');
exit();