An online order was cancelled after the kitchen had already cooked it. What happens to my ingredients?

Cancelling on the orders board puts the recipe's ingredients back on the shelf once, and puts any counted dish back too. That is right when the food was never made. When it was already cooked, the shelf now says you have chicken you do not have. Fix it with the Wastage panel on Menu → Ingredients & suppliers: pick each ingredient, type how much and a reason such as cancelled after cooking, and press Record. It comes off the shelf again and is written down as waste, so your food cost stays honest. The money side is separate: a cash on delivery order that never reached the customer owes nobody anything.