Whenever you upload photos to a photo book, it automatically creates a gallery for you and puts the photos in it. To view your galleries click on the MY ADORAMAPIX button on the navigation menu at the top of the screen (see below).
On your 'my adoramapix' page, the top panel will list your photo galleries. If you don't see the recent photos you uploaded on the visible list, click on the option to SEE ALL galleries (see below). This will take you to the galleries page.
Click on the heading of the gallery containing your photos in order to open it. Once you have opened the gallery with your photos, just check the box beneath any of the photos you would like to remove, and then click DELETE in the options to the right (see below).