Check your phone’s gallery. It will contain a folder named screenshots or a similar label. Select and delete all your unwanted screenshots.
Make sure your phone has charged the phone battery to 100%. Go to Gallery, and open the photos there. Select the pictures you don't want to delete & delete them. You can also make a copy of your pictures before deleting them. Go to Gallery>Camera>Copy Picture. Doing this will make a backup to your phone. Then, delete the pictures on your phone after you have copied them from your laptop to your camera.