Re : Deleting assets associated to a PO

use this query in database and then you can delete the PO from the UI.

delete from resources where purchaselotid in (select purchaselotid from purchaselot where purchaseorderextid in (select purchaseorderextid from purchaseorderext where purchaseorderid = ______));

Note: Enter the POID in ________

Regards,
Priya K