To delete a dashboard you have to go first to the Home page where you can find your own Dashboards and the ones which have been shared with you. Like you do on a list in any iOS device (iPad or iPhone) you have to swipe your finger right to left or left to right until de Delete button is shown next to the item. Just click in the Delete button and the dashboard will be removed from andara in your iPad. Once the dashboard is deleted from andara, it will be removed automatically from your box.com account.
A Dashboard must be created (or deleted) ONLY through andara in the iPad. andara will create or remove automatically the Excel spreadsheet in your box account. You can not create (or delete) a synced Excel spreadsheet with andara in your own PC or Mac.