Just drag the iPhoto application from the Applications folder to the Trash bin in the Dock and empty the Trash. If you have an iPhoto Library file in your Pictures folder that is empty you can drag it to the Trash in the Dock. You may not have a library if the Mac is new and you havent' used iPhoto.
You might want to experiment with iPhoto as far as creating a book, calendar or slideshow is concerned. I use Media Pro from my primary DAM (digital asset management) application and use iPhoto only for special projects. I woudn't throw it away before trying those features. You don't have to use it for all your photo organization, just a project.
OT