One of the new functions in the new edition of WP is that you plugins are grouped in active and not activate.
Above the group of not active plugins is a button that deletes the plugins that you are using.
This is a warning: DO NOT USE THE DELETE BUTTON
some of your plugins may be divided into a widget version and a normal version. If you delete the normal version the widget version will also be deleted even though it is activated (and visa versa).