I'm assuming your teacher and classmates are already aware? In high school I had to give presentations all the time. It was nerve-racking, but I got through it. I was never graded on delivery — I was graded more on the content. If your teacher isn't aware, it's time to tell him or her. They might be willing to make accommodations if you really don't want to go through it. That's what I did during college. Regardless if you're even the tiniest bit confident you can do it, I suggest you do. You'll feel better in the long run for doing so.