wmig

This simple plugin will hide posts from children categories.
It just override include_children property for hierarchical taxonomies.

Exclude Children

This simple plugin will hide posts from children categories

mustansir

This plugin allows you to add a dashboard widget that manages specific taxonomies (Such as tags and categories or any custom taxonomy). Specifically the dashboard widget makes it easy to remove a post from a taxonomy of any kind.
Those who have themes, plugins, widgets that use the wordpress taxonomy system to place posts in various lists will find this plugin especially useful.
This plugin allows you to add a dashboard widget that manages taxonomies. It easy to remove a taxonomy term applied to a post.

Category Manager

The WP Category Manager plugin makes it easier to manage any taxonomy that is used to control the posts within widgets in the presentation layer

Exclude Children vs Category Manager