Unable to add BPM Admin Role to user

Summary:

To enable managers in our customer to keep track of and manage the work the team members managers are given access to the team members work queue, Unfortunately some staff members that left didn't remove their work queue. We have tried deleting them but this is not possible.

Found a note on MoS (How to Delete Shared Views Created by Deleted Users (Doc ID 2810559.1) This suggests that the BPM Admin Role might allow us to carry out the deletion, but have not been able to add this role. Can we remove these staff members from shared work queues? Is there an alternative route other than use of BPM Admin Role?