Thanks for asking. I am sorry but it's been well communicated via our Pro launch blog post, social media channels, forum posts that you can't rollback Pro licence to X.
On the hindsight it seems that you you haven't checkout our knowledgebase resources. To help our customer get started with Pro, we have published in depth articles and video tutorials. I am sharing link of those resources that you can check it out:
Pro is a very powerful and flexible theme that can be used as a framework to create intuitive and complex website with ease. Can you please let us know the problems you are facing while using Pro? We will have more then happy to help you out with Pro.