As long as the typo doesn't affect the meaning of what you were trying to say, I say don't sweat it. Schools have to read through so many applications, I doubt they'll even notice if you accidentally left one letter out of one word. Besides, it might seem a little odd if you were to call them and point out your mistake and ask someone to correct it.
So don't worry!!! It would be ridiculous for any school to reject you just because of one TINY typo. It happens to everyone.
Good luck with your applications! 🙂