I figured out how to discard the smart previews, but my orignal question still exists. If I'm using an external drive with my catalog on it is there a point to creating smart previews? if so, what would be the best way to set it up?
If your images and the catalog and associated files are all on the external drive then you don't need smart previews. Smart previews are nice if you want to take a reduced size subset with you on the laptop and don't have the originals available. The problem with smart previews is that you can't turn to Photoshop or other external editors if necessary. So working was smart previews could in some instances restrict what you would be able to do.
Thanks! I kinda figured that was the way it worked. I appreciate the quick response Jim.