~Screenshots added by FrozenTurtle~
Open your Pantry or Toolbox and tap the red "Trash" button:
Tap on the red "-" button that appears next to the item(s) you wish to discard:
Tap the "+" or "-" buttons to change the amount you wish to discard, then hit confirm:
Note: This action cannot be reversed, so be sure you are discarding the correct amount of the intended item.
My pantry was at capacity but I didn't have enough of the correct ingredients to make any of the recipes. I searched everywhere for a clue as to how to fix this as I didn't have enough tools or gems to upgrade the capacity of the pantry.
I finally worked out that you can go into the pantry, tap on the capacity tab and there you will see a trash option where you can delete individual items. That way you can top up on the items that you need to make a recipe. I hope this helps others.