Adv. Guestbook - Remove user uploaded pic

A guest uploaded some porn onto the guestbook. I deleted the picture file but the entry still shows a box with a red x. This is logging an error on my site every time someone views the guestbook. How can I take the link to the pic out of the entry? I can't seem to edit that part in easy admin.

TIA

Personally I'd remove the entire post. Anyway to remove the picture you would have to go into phpMyAdmin or similar and delete the entries in book_pics (or whatever it's called) that has the same ID number as the post in question. Complicated I know but at present the only way to do it.