I just downloaded and it's fine. It is an .ai file so are you opening it in Illustrator?
Yes I am using Illustrator from CS6. The probleem seems to be that the text 'Book Title' and its background are the same layer and can't be edited in the way a normal vector layer can be edited. In this way I can't delete the text without deleting the background. No objects are grouped, and none of the normal layers are locked so that isn't the problem. When I am zooming in, I notice the pixels becoming visible and so I can't conclude anything else than that the text and background are just one bitmap, covered with other layers.
I am not sure if this has anything to do with it, but when I open the file, I receive a warning that Illustrator CS6 uses a new support for 9 slice scaling for symbols and that I have to choose if I want to keep the 9 slice scaling. Could this be relevant?
I am sorry if I sound kind of vague but I am operating on a dutch version of Illustrator so I don't know if I am using the same words and concepts as used in the english Illustrator.
I can't edit the title either, it appears to be part of the colored image. I'll report the image to our content manager and I've granted you a license credit for the image. We apologize for the inconvenience.
Thank you very much, that's great.