This plugin comes with feature that allow to delete the comments based on category,users or all at once. It's best for victims of spammer attacks
Allows one to mass delete WordPress posts and pages according to the specified conditions such as date range, post status, post content, etc.
A quick way to delete all pending comments. Useful for victims of spammer attacks.
NukePiG allows you one-click deletion of all your blog posts, pages, tags, categories or links.