The finance admin can still send back an approved expense when changes are required. When a report is sent back, it moves into Sent Back state and it has to be re-submitted by the user after rectification. The report once again is submitted for approval to the approvers, following the approval hierarchy.
To reject/send back a report:
Navigate to 'Reports->Verify'
Open the approved report
Click on the down arrow next to Move to Payment Queue.
Click on the Send Back option from the list of options that pop down.
You are required to enter a reason for sending the report back.
The employee/user would receive an email notification about the report being sent back along with the reason as stated by you.
Send Back also changes the status of a report to Sent Back from Submitted.