Access your My Files by clicking My Files in the main menu. Hover over the folder name, click the three dots icon to the far right of the folder, and click "Delete". Keep in mind that any documents saved to the folder will also be deleted.
Deleting a folder is permanent, once you click Delete, it's gone forever. However, if the folder contained a document that you have created through a SmartGuide Interview, you can recreate the document. Click on SmartGuide Interviews in the main menu, select the document, and click "assemble". Your document will be reassembled and placed into your My Files.