Standered "PO" Delete or Sheduling PO deltete

Hi.. SAP Professors.

In My Client place My user want to delete PO, mean with PO number itself as well as we want delete scheduling agreement PO also,How can I delete PO number or scheduling PO.

EX:when we create PO it will generate one document number ex:5000000001

This Number Itself I want to delete is there any procedure or t.code.

Kindly suggest me about this issue...awaiting for your replay..

Cheers

Madhu