Sorry but we still do not understand. Do you mean to remove current demo content and import another pre-built website? Is that what you would like to do?
You can use Builder >> SEO option located on default WP editor but this would only transfer Muffin Builder into shortcodes which probably won't work on your new theme.
Comments
sorry but we do not understand your question. Could you try to explain once again what you would like to do exactly?