SAP Sales and Distribution
This error message is issued when Purchase requisition created against sales order (third party services) is manually deleted using ME52N.
In third party sales process , Purchase requisition is directly created from sales order with account assignment X and item category S. Since the PR is created from sales process , the deletion and modification activities should be performed from sales order.
This a standard system behavior , and for deleting the PR's created , delete the line item from sales order this will set a deletion indicator in the PR.
But in some cases , say a PO is manually created against the sales order and there is parked document created in MIR7 , and when sales order line is deleted , PR is set with a deletion indicator. When the user is trying to delete the parked invoice document in MIR7 , he might get the same error message. In such exceptional cases where , PO / PO cannot be deleted due its reference to sales document but needs to be deleted, use the correction program in note :
19028 - ME52 PReq cannot be deleted E06269(third-p.prcssng)
This correction program removed the link of the subsequent document PR/PO from the sales order and the document can be deleted manually using ME52N/ME22N.
Reference
Third Party Sales Process Basic Understanding
19028 - ME52 PReq cannot be deleted E06269(third-p.prcssng)