I figured I had better start another, more accurately-named thread for this.
Yes, I have deleted the sample books/articles in question from my nookbook Library in my Account at bn.com.
And I did try "Check for New B&N Content" on my nook in My B&N Library. The titles are "greyed-out" but they are still there. They are showing as "archived." I can unarchive the articles (freebies) which are NOT showing up in my online nooklibrary, btw.
A lot of these were freebie articles...The seem to be permanently lodged in my nook. No big deal, but I do have a lot of customers with this question, too.