This may happen if pages are added to the site at the top level and the editor has "Automatically organize my navigation" checked.

If the Help page appears in the navigation sidebar and you want to remove it, follow these steps:

1. From the main page, click "Edit sidebar".
2. Under "Navigation", click "Edit".
3. Uncheck "Automatically organize my navigation".
4. Highlight the Help page by clicking on its title, then click the "X" box to the right to remove it from the navigation.
5. Click "OK".
6. On the "Customize your site layout" panel, click "Save changes"

  These instructions were provided by Chris 03/03/2010