Wendy,
Go to your Scrapbooks and find the guestbook and edit it there:

dashboard>Srapbooks> Your scrapbook

cannon4700, thanks for the response. I went to the guestbook in Scrapbooks but could find a way to edit it there. I deleted it just to see what that did. When I went back to my site I was still unable to get it to hi-light in edit mode when I mouse over. So I still can't edit it there. Is there a way to make the guestbook edit-able in Scrapbooks? Did I blow it by deleting it there?

Well...
Try refreshing your cache (via dahsboard) and clearing out your browser cache as well.
My experience has been that if a block came from a scrapbook and you delete the block out of the scrapbook then it should disappear on the pages it appeared.

Are you using any custom templates or other Javascript?

Cannon4700, I did clear my cache and I am using the Plain Yogurt theme. As far as I know I'm not using any "custom templates." I was not able to delete the guestbook from my site even after I deleted it in scrapbook. I'm getting scared it's there forever. Is there anything else I might try?

cannonf700, Okay this is a little weird. A few moments ago I went on my website to add a blog and I thought I'd just try to delete that persistent guestbook again. In edit mode, I moused over, it hi-lighted and then I selected delete and it worked! I don't know why it worked today. Did someone DO something? Anyway I'm sooo delighted to get rid of it though perplexed as to how it happened.