In Reply to Dhananjay Sandbhor:
I'm curious about this as well. The link provided below just informs (and warns) about how to delete processes not answering the original question of "should we".
Most workflows have a Primary Business Object (PBO) linked to them. It is best practice not to delete, but there are cases where this causes huge performance issues when they are:
There are cases where the lifecycle spawns multiple task or workflows. So, its the process that has to be deleted and a more efficient Lifecycle and its WF process has to be implemented. So what to do...
Deleting a terminated, completed orexecuteddoes not change the history of the PBO. I've been at some customers where we have to delete the processes because it is taking up the resources of Windchill app due to queries in large number of process: