将值设置为""，过期日期设置为昨天(或过去的任何日期)

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

然后，cookie将在下次页面加载时过期。

你可以试试这个

if (isset($_COOKIE['remember_user'])) {
    unset($_COOKIE['remember_user']); 
    setcookie('remember_user', null, -1, '/'); 
    return true;
} else {
    return false;
}

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cookie的值设置为false就可以取消设置:

setcookie('cookiename', false);

当您为时间输入0时，您的意思是“现在”(从现在开始+0实际上是现在)，浏览器会删除cookie。

setcookie("key", NULL, 0, "/");

我在chrome浏览器中检查了它，给我:

Name: key
Content: Deleted
Created: Sunday, November 18, 2018 at 2:33:14 PM
Expires: Sunday, November 18, 2018 at 2:33:14 PM

$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.