Being able to undo when you want to convert a inventory to non-inventory isn't available, mcfa1981.

You need to manually deactivate the inventory item and create a new one with the correct type. For additional information, you can use this article as a reference: Add, edit, and delete items.

I'm also adding this handy link for your guide with QuickBooks Inventory: Receive inventory.

Keep on posting if you have other questions about inventory or any QuickBooks related concerns. I'm always here to help.