I'm currently trying out the evaluation version of ViArt Shop Enterprise. I deleted the demo products that come with the program, but I noticed when I add a related or accessory product, there are around 16 demo products listed, none of which show up in the main products page or on the front-end of the shop. How can I delete these items? And is this a bug?

No, it isnt a bug. You will have to go into the database using phpmyadmin, and delete them manually.
 
Kind regards
Kim