I am trying to export files to a thumb drive to free up space

You can actually download all the uploaded files before deleting the submissions. Here's how:

1. In My Forms, select the form and then click the "Submissions" button.

2. In the Submissions page, scroll down and you'll see the "Download All Uploads" button above the Grid Report.

You may also use the Data Export tool in order to download your forms in HTML, submissions in a CSV file and the file uploads. All of this will be in a .zip file. Please refer to this user guide: https://www.jotform.com/help/374-How-to-export-all-of-your-data-at-once.

Hope that helps. Let us know if you have any question. Thank you.