I made the same query not long ago as I was also quite new in CS and had not much experience uploading photos to CS. I later foundout that you can remove teh "unwanted" photos by doing this :
1. Login to your CS Photo gallery
2. Click on "My Photos"
3. Select the photo you wish to remove by clicking on it.
4. One row below the "keywords", select the icon for "Edit Photo".
5. You should be able to select the option to delete the photo just above the "Submit changes" box.
Good luck and let me know whether you encounter any problems. Cheers.