优化删除有主题的分类的用户体验

[bloomexperiment (Tracey)]

另有一个管理员在使用当前 删除类别 行为时遇到问题的案例链接：

I'm really convinced that I'm being toyed with by a community software

I can’t find the area to delete “Channels” and when I try to delete a category it tells me “There are channels in this category that can’t be deleted.”