Jive SBS comes with a set of widgets people can use to customize pages. If you don't want certain widgets to show up where people can customize page layouts, you can remove them using the admin console.
Admin Console: System > Settings > Widgets
You can delete widgets by clicking the Remove button. For a list of the widgets included with the application, along with descriptions, see Designing Pages with Widgets.
You can also add new widgets. At the bottom of the page, under Add a new widget, enter the fully-qualified class name of the class for the widget you're adding, then click Add Widget. The JAR containing the widget you're adding must be on the application's classpath.