In SpreadsheetWeb Hub each transaction constitutes a version of your application. When user publishes a transaction, the transaction becomes locked down and all your changes are committed to the production/published version of your application.
The Transaction History lists each published version and in progress (not published) transaction, if there is any, up to server-based configurable limit.
To view an application’s transaction history, go to your Applications page and click on History button.
A list of transactions will load with IDs, publish status and start and publish date.
You can sort transactions by those criteria and download workbooks belonging to each transaction.
If a workbook is not yet published you can delete it.
If there are any modifications on the application, those will be deleted but last published version of the application will not be affected.