If payment is not made within 180 days from the date of Invoice, we are required to reverse ITC availed. How can we print a list of payments not made within 180 days ?

You may print ITC Reversal (180 Days) report by clicking on GST Docs -> Reports -> ITC Reversal (180 Days) Report.

This report should be printed for each month and liability should be accounted for in GSTR-3B.