How is the vendor returned processed without a purchase order reference? | SAP-MM

You first need to observe the Return column and then click item detail, MIGO_GR, goods receipt for purchase order. If the intention is to deduct the stock, then movement type 161 is used; otherwise, 162 is used to undo the changes. Lastly, it is required to ensure that the document is return purchase order. Afterwards, the document is saved.