2.8 Unregister Widgets

I am attempting to make a cleaned version of WordPress that I can use for client websites, and therefore I want to be able to remove all of the default widgets and simply add in the ones I want to use by commenting out a line in the function.

I have tried using the following code:

add_action('widgets_init', 'remove_default_widgets', 10);
function remove_default_widgets()
{
unregister_sidebar_widget('pages');
}

And also the code that was found in this post

function unregister_problem_widgets() {
unregister_sidebar_widget('Calendar');
unregister_sidebar_widget('Search');
}
add_action('widgets_init','unregister_problem_widgets');

Unfortunately neither of them have worked. Is there anything additional I have to put in my template file, or any calls I have to put anywhere else. Or has the way this is handled changed?