Invoice in workflow Rejected, however status of invoice remains as "Parked and Completed".

[muhammad789]

Would appreciate if I can get some help in regard(s) to one of my invoices in my system, or any further invoices in the future if the same issue occurs.

The Issue : 
Invoice has been rejected in the workflow, however the invoice in the PO remains as parked and completed. When attempting to manually delete the invoice in MIR6 , the option to delete the invoice is greyed out. When checking in the PO, in "Purchase History" tab, the invoice is still parked there.

Troubleshooting / Re-produce Error : 
The cause of the issue was most likely due to when the invoice was rejected, another user had the PO opened causing PO / Invoice to be "In process" by another user. When looking at the technical item(s) in the workflow, it does return that :

" E-ME-006-User xxx already processing Purchase Order xxxxxxxxxx--000000--AM.. "

My Question
What t-code / report should I use to fix this issue, is there a way to reprocess the reject status or update the invoice status? I want to specifically delete this invoice from the PO, so that it no longer is shown in "Purchase Order History" tab (at item level) of PO.