(PECL apcu >= 4.0.0)
apcu_delete — Removes a stored variable from the cache
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 A apcu_delete() example
<?php
$bar = 'BAR';
apcu_store('foo', $bar);
apcu_delete('foo');
// this is obviously useless in this form
?>