According with the official example (Secure Web Content), I have to use a form and a button with the aim to perform a logout with Spring Security. Is there a way to use a link with Thymeleaf instead of a button?
You have to use a form for log out. If you really want a link, you can use JavaScript to have the link perform a POST on a hidden form.
<a href="javascript: document.logoutForm.submit()" role="menuitem"> Logout</a>
<form name="logoutForm" th:action="@{/logout}" method="post" th:hidden="true">
<input hidden type="submit" value="Sign Out"/>
</form>