Hi
The reason for this is that when you post consumption against a production order the system transfers the cost of the RAW materials into Production - Work In Progress, then when you post output the system transfers the total value of the raw materials from WIP into Inventory
The reason why the system wont let you remove the order without posting output is that these values will be left behind in the WIP,
What you need to do is post an output of 1 and then finish the production order, Run the adjust cost after finishing the production order to ensure the costs are fully updated, you can then negatively adjust the 1 qty out of stock
Cheers
Nev