In edit mode you can easily clear the board by clicking in one of the bearoff trays. It's often easier to start setting up a position with a empty board, so this feature is really handy. When you click on one of the bearoff tray, all checkers will be moved to the bearoff.
Click in the one of the areas marked with a red ellipse to clear the board.
You can also just as easy generate the initial position by clicking the opposite trays when in edit mode. Clicking in one of these trays puts all checkers back to the initial position.
Click in the one of the areas marked with a red ellipse to get to the initial position.
Note that the bearoff trays change side when the board is displayed with clockwise movement.