Scared to fight, how do I get rid of it?

I love MMA boxing and kickboxing but being a martial artist myself i get scared when i want to fight someone, even someone i know i could beat up. I want to stop this because I'm a good fighter but I don't want to be scared of anyone. Please help me to control this. BTW i never used to get scared in the past, it happened in the 8th grade for some reason IDK y.