ManageEngine ServiceDesk Plus provides an option to Close PO manually on receiving all the items and the invoice, or after making the payment.
To close a Purchase Order,
Click the Purchase tab in the header pane to open the purchase list view page.
Click the PO Name link of the Purchase Order to close. You can use the Filter drop down to sort and select the PO.
From the PO details page, click Actions drop down -> Close PO option. The Close PO dialog pops up.
Enable Send Mail Notification check box.
By default, the email address of the technician is displayed in the To field.
If required, you can modify the Subject content manually and type in the message text for mail notification in the Description field.
Click Send button. The status of the purchase order is changed to Closed.