I goofed. I thought I knew what I was doing in importing into Lightroom. Before I knew it, all the photos on all my drives, 50,000 photos, were being imported. I do not want all of them and I would like to start over. If I delete the catalog will that delete the photos from Lightroom, but not from my drives?
Yes, you can delete the catalog and it will not delete your images,once you start with new catalog you can select a folder under the source which you want to import.
You can uncheck the images which you don't want import in Lightroom.