(PECL imagick 2, PECL imagick 3)
ImagickPixel::destroy — Deallocates resources associated with this object
本函数还未编写文档，仅有参数列表。
Deallocates any resources used by the ImagickPixel object, and unsets any associated color. The object should not be used after the destroy function has been called.
成功时返回 true。