i wnat to delete last import and import them again

I imported 170 pictures of a concert. Some are recordings but the video recordings are upside down and iPhoto wont let me change/rotate them The camera is new so I have found how to rotate the videos now in the camera settings.. I tried to upload again but iPhoto says already imported. Is it possible to import again? Is is possibe to delete last import and start again and upload all of them again?? Thanks for any help anyone can offer.