I don’t think you would be able to re-use that. There are many dependant files that reside outside the main directory, probably registry entries too.
You are best just re-installing again. The good news is that the store version syncs every single setting, and that takes much of the pain out of it. Even the control profiles are saved!
All you have to do is re-download the world updates etc from the content manager and then re-install your third party add ons.
It was quite a painless experience when I did it. Within about 30mins of completing the install. I had re-installed Fenix, PMDG, FSLTL and Navigraph and re-dropped my favourite scenery into the community folder.