If you no longer need a specific report (a folder containing several receipts and/or distances), you can delete it.
iOS or Android app
Go to the Reports tab:

Tap the report you would like to delete.
Tap Delete.
Web portal
Click Reports to go to the Reports tab:

Click the ⋯ button and select Delete:

Confirm the deletion.
This operation does not delete any receipts associated with this report.
To view receipts no longer associated with a report, see Viewing All Receipts.
