How to delete a k2 5.1 workflow instance from database?

Hi achand,

You may delete a workflow instance in the K2 management site:

https://help.k2.com/onlinehelp/k2five/userguide/5.1/default.htm#K2-Management-Site/Workflow_Server/InstancesTab.htm#Instances

Hi,

Are you referring to instances which have already been completed but are still found within the K2 database? You may want to perform Archiving if that is the case. Please refer to this KB. You would need to log a K2 Support Ticket to request for the archiving script.