Delete old content and recreate site on the same domain name
If you'd like to delete your existing website, and recreate it, just simply create a new website selecting the same domain name.
Here's a guide that will help you get started: https://user.rvsitebuilder.com/docs/7.3/en/website-design
Please note, this will completely overwrite the current content.
Permanently delete all*
If you want to delete content permanently from your domain name, you can do it by following guide. It will delete all folders and files related to RVsitebuilder.
*This will permanently delete all and cannot restore.