It is not possible to revert a web site once after it is saved, I would recommend that you add this to the ideas section over here, http://forums.adobe.com/community/muse/ideas
What is the error that you get when you try to publish ?
I had just changed the "publish to" directory and credentials for upload, from a business catalyst temp site to
an already existing .com hosted on business catalyst. When I publish now, it runs through html page upload then slows to crawl
There is some issue on the business catalyst server which is known to the engineering and they are working on it right now, http://www.businesscatalyst.com/support/system-status
Try it after some time please.