Stack Delete?

[aki15]

Hey...
I'm making trigger that will delete 1 item and make another one like *Improving it*
-You need to pay 5 gold and have that item - in this situation (Iron Ore) and when u pay 5 gold you will lose 1 Iron Ore and Get 1 Iron Bar...
-I use Stack and Split system, so when Player has more than 1 Iron Ores stacked, he will lose all of them...
How can i make this, so it will lose only 1 stack???

-EDIT:
-Done this by lowering 1 charge of item...

 

[Dr Super Good]

You need to detect when the charge of the item becomes 0 and remove it. 0 charged items still exist as it reserves 0 for infinite charges.