Hi, I have a PO in NetSuite and i have created some item receipts. Is there any way to undo this via API?

Knowing the PO you should be able to create an Item Receipt search where the createdfrom = the PO, then you can delete those receipts.

so i can get @alien4u all the item receipts when i fetch the PO?

Fetch the PO, and then search for the IR where createdfrom field is that PO.