Use a similar action as storing food (right-mouse drag), you can drag a food to the trashcan (to the right of the refrigerator) to delete a food from the table. One advantage for removing a food this way is that you can right-click on the trashcan and retrieve the previously deleted food. To clear trashcan of its content, click the "Empty" button.
A third way of deleting food is by using the "Clear" button on the Remote control. Click this broom-like icon to clear the table of all food (plates and the Meal tray excepted). A second and third consecutive clicks will purge the table of plates and Meal-tray.