错误现象：
Error response from daemon: conflict: unable to delete a2f2e369e78e (cannot be forced) - image has dependent child images
解决方法：
语法：docker rmi [OPTIONS] IMAGE [IMAGE...]
采取 docker rmi REPOSITORY:TAG 如上图
错误现象：
Error response from daemon: conflict: unable to delete a2f2e369e78e (cannot be forced) - image has dependent child images
解决方法：
语法：docker rmi [OPTIONS] IMAGE [IMAGE...]
采取 docker rmi REPOSITORY:TAG 如上图