Can I create a site without using any of the provided themes. If so, how can I remove what is assigned and start all over again?
You must assign a theme to your WordPress site in order for it to work.
This article covers the basics of WordPress theme development:
But creating a custom WordPress theme from scratch is quite challenging. Most people prefer to start with a theme or a framework, and then simply customize it to fit their needs.
If it’s primarily custom layouts you’re looking for, you might look at Beaver Builder. It’s a plugin that enables you to further customize your installed theme, adding custom page layouts to better fit your needs.
Again, it’s helpful to first find a theme that gets you close, and then use a tool like Beaver Builder to modify it as little as possible.
Many theme developers use a framework like Genesis, and then create custom child themes to create a custom look and feel without having to create every little function and feature from scratch.
Once you’ve purchased and installed Genesis, you can then use a plugin like Genesis Design Palette Pro to further customize the look and feel of your entire site, using familiar tools within the WordPress admin area, without diving headlong into code.
Another popular alternative is the Divi theme, which includes a proprietary user interface for customizing the appearance of nearly every aspect of your site.
Canvas is another theme with customization tools built into the admin area. It also includes support for WooCommerce and much more.
Take a look at each one of these tools and see which one will best fit your needs. Hope this helps!