“How do I remove the default widgets that come with WordPress?” — I heard this at least five times in the last two months. The solution is to use the Remove Default Widgets plugin that I wrote earlier this year.
It’s better than using unregister_widget for each registered widget in your functions.php file (or wherever), because a new version of WordPress might ship with a new default widget, which is not in your list, rendering the method non future-proof. Also, why waste the time (and CPU cycles) and register a bunch of widgets, to unregister them soon after?
The plugin I mentioned simply tells WordPress to skip default widgets registration. All of them. Even if WordPress 3.6 adds twenty more widgets, this plugin will still work.
Always wanted to know how to do this. Thanks for this plugin.