This function archives process instances of a process definition. 

Archive process instances functionality allows the user to archive the instances for the selected process definition.  All instances of the process definition that are non-waiting will be archived.

On the Process Definition page, you have the control to select the process from the table and initiate the archiving process by clicking on the Utils - Archive Instances menu option.

An Archive Instances popup window is displayed for confirmation, as shown below. You can click OK to proceed. All the process instances of this definition are archived. 

Note: Archived instances cannot be undone for now.  

Navigate to the Status—Settings—Archival menu option. The Archival Settings page is displayed below. The application archival service engine archived and removed the process instances, form instances, and events on this settings page.