Hello,
Thank you very much for choosing our theme and for contacting us.
I hope you have the backup of the initial site. If you have, restore the site. I would suggest you to create a clean WordPress installation on a testing platform, install the theme, upload the demo, configure your site, remove the demo content you do not need and import your content from the initial site, then when everything is ready you would be able to migrate the site from testing to live domain and it would not influence your live site.
Best Regards