how to handle free(free of cost goods) goods with price in PO

Hi Experts ,

We have one issue , We have some free of cost goods , bur our commercial people wrongly mentioned price and even not ticking on free tick box while making PO , and subsequently they posted goods reciepts. Now in SAP open GR/IR accounts are showing with value . Kindly explain how to nullfy them ,

Thanks in advance

Regards

Venkat