To delete an existing dashboard, simply expand the Dashboard Selector and rest your cursor over the dashboard you wish to delete. A small set of icons (depending on the permissions in your default user role) will appear to the right of the dashboard name. Users who don’t have sufficient permissions will not see the Edit (pencil) or Delete (trashcan) icons, but all users can edit or delete their own Private dashboards.
Click the trashcan icon to bring up a popup delete dialog. A confirmation dialog will appear, allowing you to delete the dashboard or cancel and return to the list control.