Bulk editing of posts is one of the most useful features that WordPress offers. It’s also one of the most fatally flawed, because while you can easily add categories and tags to large numbers of posts at once, it’s impossible to remove large numbers of posts from a category using WordPress’ native CSS. I’ve figured out two ways to circumvent this, but haven’t attempted either one just yet.
The first is the Bulk Move Plugin, which allows you to move a group of posts from one category into another category. It’s inelegant and I haven’t yet figured out how to get it to remove groups of posts from a category, but it’s a decent option if you’re looking for a really simple fix and you don’t want to fiddle with CSS.
For a more permanent/integrated solution, I found some CSS edits that will apparently add an option to remove posts from categories in the bulk edit menu. Ultimately this is the option I want to use, but fair warning: the code was written for WordPress 3.2, which is now obsolete.
As my CSS skills are basically nil, I’ve used the first option to shuffle a bunch of posts from “Uncategorized” into a different category. It worked for me, but eventually I’d like to implement the CSS fix.