$cookie_name = "my cookie";
$cookie_value = "my value";
$cookie_new_value = "my new value";

// Create a cookie,
setcookie($cookie_name, $cookie_value , time() + (86400 * 30), "/"); //86400 = 24 hours in seconds

// Get value in a cookie,
$cookie_value = $_COOKIE[$cookie_name];

// Update a cookie,
setcookie($cookie_name, $cookie_new_value , time() + (86400 * 30), "/");

// Delete a cookie,
setcookie($cookie_name, '' , time() - 3600, "/"); //  time() - 3600 means, set the cookie expiration date to the past hour.

如果您将cookie设置为过去过期时间，浏览器将删除它。参见setcookie() delete example at php.net

只要将过期日期设置为一小时前，如果你想“删除”cookie，就像这样:

setcookie ("TestCookie", "", time() - 3600);

or

setcookie ("TestCookie", "", time() - 3600, "/~rasmus/", "example.com", 1);

来源:http://www.php.net/manual/en/function.setcookie.php

你应该使用filter_input()函数来处理访问者可以输入/操作的所有全局变量，如下所示:

$visitors_ip = filter_input(INPUT_COOKIE, 'id');

你可以在这里阅读更多:http://www.php.net/manual/en/function.filter-input.php和这里:http://www.w3schools.com/php/func_filter_input.asp

我在php中使用这个，它工作得很好。

function cookie_unset()
{
    setcookie("cookie_name", "", time() - 3600, '/');
    unset ($_COOKIE['cookie_name']);
    //done
}

很简单!

setcookie("cookiename", "cookievalue", 1);

$cookie_name = "my cookie";
$cookie_value = "my value";
$cookie_new_value = "my new value";

// Create a cookie,
setcookie($cookie_name, $cookie_value , time() + (86400 * 30), "/"); //86400 = 24 hours in seconds

// Get value in a cookie,
$cookie_value = $_COOKIE[$cookie_name];

// Update a cookie,
setcookie($cookie_name, $cookie_new_value , time() + (86400 * 30), "/");

// Delete a cookie,
setcookie($cookie_name, '' , time() - 3600, "/"); //  time() - 3600 means, set the cookie expiration date to the past hour.