If you want to delete a food from the storage, make sure that the inventory mode is in "Move." Then drag food to the trash can (left or right mouse-button). To clear the whole storage, use the round "Clear" button on the bottom-right section of the screen, a warning will ask you to confirm deletion of all food from this storage.
Remember that appliances such as refrigerator, freezer, microwave and oven also open up and can store food. Cooking functions will be added in later versions.
Condiment storage is located right above the microwave. Right-click on it to open up and retrieve the desired seasoning.