Don't feel bad. We've all messed up our posting. I don't know what it is--maybe it's the idea that we're making our work public for the first time. Strangers are going to see our stories and tell us what's wrong with them. It gets a person rattled, and we miss the cues that direct us in our posting. I've seen this happening a lot lately, and I don't know if it's deliberate.
There are two things that could be happening:
1) In the event that you've re-posted the same chapters (or story), you're paying unnecessary points. You could delete one, but I don't think you can remove (delete) a work and keep the reviews. It's best to deactivate them, as Suin says. You'll be the only one able to read them, so you can still see the reviews.
2) If your book's chapters are appearing as individual postings rather than parts of a whole, you've missed a cue. From the drop-down menu (under your name) at the top of your home screen, select your portfolio DON'T select 'Add new content.' Select the title of your book. A little drop-down menu will appear at the right. Select the option that says 'add chapter.' Then follow the directions.
I hope this helps. If not, someone else will have what you need. JP