How do I undo an update to use a previous version

My web service was working on an older version of BSS. I've posted the problem on the Bugs forum but was wondering how to remove an update so BSS runs on an older version. I suspect the update broke it.

Also, I exported the exact BSS page to a local folder on my machine. Then I loaded the page in the browser The web service with the exported page works when loading it locally but when running it from BSS it doesn't connect.

If I can revert to a previous version, then I can continue to work until I get a fix from Bootstrap.