You can delete Boards from the Dashboard
If you are in the Board that you want to delete or in another board, first return to the Dashboard by clicking/touching the Ideaflip logo - top-left of your screen to reveal the main menu and select Dashboard.
In the Dashboard (the first screen you see when you log-in) you will see mini screenshots of all of your boards. Click/touch on the board that you wish to delete. This will enlarge the screenshot and give you some options below. Click Delete and you will be taken to a confirmation screen. Select Delete again and your Board will be removed from Ideaflip.
If you want to delete all of the contents on a Board but not delete the Board itself then you will need to use the 'Create a temporary Group' method to delete items en-mass. Learn more [How do I delete stuff?]