Once a Requisition has a chosen Vendor, it is eligible for Action: Create Orders. This process creates a linked PO record and advances the Requisition Status from Open to Released.
If the user, intentionally or accidentally, deletes the resulting Purchase Order, the workflow comes to a "dead end".
The Request document is in Status: Closed, yet the line on the Request is stuck in Status: Requested. And the Requisition document, in a Status of Released can neither "let go" of the Request, nor can it spawn another PO. Similarly, the PO form does not allow creation of a PO and "link back" to a Requisition line.
How does the customer associate a new PO with the now-frozen Request and Requisition documents?
Per Acumatica Support (RE: [Case #142071] Create new PO from released Requisition - DSD Case # 8190 , May 29, 2020) this action is not possible. Undesireable work-arounds include re-creation of Request and Requistion, or the use of Notes, Description or UDF/Attributes on a new PO.