Cancel \ Delete GRN

We are currently on Vantage 8.03.409C and we have an issue that requires us to delete or cancel a GRN.

THE ISSUE:

We need to delete unmatched GRN where purchase invoice has not been matched against GRN at time of invoice processing.

The invoice may preced the GRN and we are left with GRN sitting there.

Has anyone ideas on how to clear GRN