Yes, please go ahead and erase all the content on bluemarblecafe.wordpress.com. I would like to ensure the next semi-experimental version has a cold start.
This is done. If you need to set up the Featured Content slider, please follow the guide here, in the section titled "Featured Content Slider":
As for my comment about the reset recipe not working: I have a couple of experimental sites with you, and after switching between multiple themes I realized that some structural content persists, even if I try to hew closely to the recommended procedure for clean up. Of course I may well have slipped up, but it will be a while before I understand enough about WordPress admin and basic structures before I can be sure either way.
Gotcha. The general things to watch out for when switching themes are widgets, menus, and custom CSS, outlined in a bit more detail here:
Other content does stay present though, and different themes may display that content in different ways. For example, some themes have a Featured Content slider while others may have a Featured Content grid -- while others don't have a Featured Content area at all.
If you need help with anything specific after a theme switch, feel free to post again and we'll always be glad to take a look and see what may have happened.
Related question: Can you please clarify for me the second option, that of deleting the site entirely? The instructions warn (I'm parsing a bit) that the URL itself will be deleted permanently and remain unavailable in the future. Am I reading that right? If the domain name is freed up by a hard delete, I would simply do that and start afresh.
Deleting a site also makes the domain unavailable again, either to you or anyone else, so it's best never to use the "delete" option if you think you might want to use the domain again, as you won't be able to get it back.
If you want to reuse the same domain but delete all your content, you can do that in your dashboard. The bulk-delete options are currently only available in the WP Admin dashboard, which you can access by adding /wp-admin/ at the end of your URL.
If you truly have a very large amount of content (i.e. hundreds of posts, pages, images, comments, etc.) staff can also empty the site for you on request.
Let me know if this answers all your questions!