> How do I clear the thumbnail images from photos I have deleted.
How did you delete the photos? Did you delete them from within LR, or behind its back? You're supposed to perform all file organization inside LR once you've imported files because it's a catalog that stores thumbnails, rather than a file browser. On the thumbnail you want to remove, right-click and choose Delete, to remove the photo from your hard drive, or Remove, to remove the photo from Lightroom, but leave the photo on your hard drive. If there IS no Remove command at the bottom of your context menu when you right-click, because you've deleted the photo itself, a LR guru will have to help you with the next step to take. It should be easy to simply remove from LR, but I've not deleted any photos from the hard drive without first removing them from LR, so it may not be as easy as I think it should be. . .