How can the HTTP headers in a browser be used to troubleshoot issues related to cookies not being deleted in PHP?

When cookies are not being deleted in PHP, one way to troubleshoot the issue is by checking the HTTP headers in the browser. By inspecting the response headers, you can verify if the cookie deletion process is working correctly. If the "Set-Cookie" header is present with an expiry date in the past, it indicates that the cookie should be deleted. If the cookie is still present in the subsequent requests, it might be due to caching or browser settings.

// Delete a cookie by setting its expiry date to the past
setcookie('cookie_name', '', time() - 3600, '/');