Once an item card has item ledger entries, the system will not allow you to go to the item card and change the item type. You have two options, but I would first ensure the incorrect items have a quantity of zero in inventory, and are not present on any document/journal lines:
1. Stop using this item card, and create a new item with the correct item type. You can block the old incorrect item, and add a variation of z or zz in the item no. so it sits at the bottom of the item list and you can also reuse that item no. for the new item card.
2. You can use a configuration package for the item table to modify the item type and keep using the same item card. The configuration package would be for the item table and only contain two fields, the item no. and the item type. Configuration packages allow to skip the validation for specific fields so we can make it skip the validation on the item type to allow us to change it. Here is an example:
Also, if the existing items have inventory in stock, you can use the item journal with a negative adjustment to get them out of inventory. I am guessing you would want to do so regardless, as these items should have been expensed rather than sitting on your balance sheet. Something to keep in mind is that doing a negative adjustment in the item journal will Debit your Inventory Adjustment Account and Credit your Inventory Account. Without knowing what your chart of account and other setup looks like, an accountant might also want to then re-allocate the amount booked in the Inventory Adjustment Account to an expense account for your items with the type non-inventory, as again these items should have been originally expensed.
Valentin Castravet
Zander ERP Services