How does system administrator release a stuck expense report?

We are using ebs version 12.1.3

User has expense report out there that is pending manager's approval. The manager didn't respond. Then the notification seems like go to system administrator end. However, I do not see anything on the system administrator's work list, nor did I receive any email notifications. I went to the workflow administrator and looked at the status diagram and it does show that this expense report is still stuck in the approval process. Where can I as system administrator to release this expense report and move on the workflow process, or re-assign for the manager to approve? The current status of expense