To do this:
- In the Finder, choose Home from the Go menu.
- Open the Library folder.
- Open the Widgets folder.
- Look for the widget that you want to remove from the Dashboard Widget Bar, and drag it out of the Widgets folder. If you want to delete it, put it in the Trash and empty the Trash.
This works only for widgets that you've installed (such as those that you can download from here). If you haven't installed any, you won't see a Widgets folder in your Library folder. Widgets that were installed with Mac OS X 10.4 are not intended to be removed from the Widget Bar.