How to drift away from a friend?

Okay, so I have this friend. We were very close at the beginning of the year. Now, she is WAY to clingy and all over me. She treats me like I would be her boyfriend! She always tries to please me, and has to be around me, talk to me, or call me 24/7! It's really annoying. WHen she thinks I'm even the slightest bit mad at her, she calls me or txts me like 20 times apologizing, and asking me to call her. At recess or at lunch, she always has to be by me. I really just want to be my own person and focus on my grades. So, does anyone have ideas on how to drift away from a so called Best Friend? any help is greatly appreciated, but the best answer gets 10 points :)