Change the status of a WF parent ID to Complete

Hi Gurus

We are using WF for approving Credits/Debits/Returns. on a few very low $ values requests we have manually removed the billing block and processed them . At the same time we have deleted the corresponding WF items from User inboxes so that they no longer have to deal with these requests. But we have the WF status as " In process".is there any way to manually change the status to Complete.

Thanks

PM