You can write-off products in the Administration panel:

Products without recipe are written-off on the Warehouse\Products write-off screen.

Dishes with recipe are written-off on the Warehouse\Production catering screen.

If you want to write-off products automatically, set the corresponding flag in the Administration panel: Settings\Accounting policy\Write-off automatically. Thus products will be written-off automatically after every selling.

Press the Generate writing-off sales button on the Warehouse\Products write-off screen or on the Warehouse\Production catering screen and the corresponding products will be written-off as of pressing this button.

If there is a product balance in the warehouse, it will be written-off with an allowance for its average-weighted price.

If there is no balance and writting-off into the red is authorized (the flag is set Settings\Accounting policy\Allow to write-off if product balance is absent), the program will write-off at the last receipt price. The receipt price is defined in the Administration panel: Warehouse\Products arrival.