How to deal a bad student in a class

I am a maths teacher by profession teaching in a pivate school. Everything is fine except one student. He is kind of mthrfckr, always talks back, doesn't respect me and always giggling and dloing nonsense stuff. Even the school headmistress (HM) is inclined towards him coz she brought him to our school and they don't want to loose admission. Since, this a new school so they are dying for admission. Now, this mf student always talks bad about me among his friends and since HM is also towards him he knows that i can't do much about him. He is a spoiled brat and even his parents are ignorant. What should I do? This fckr is the single reason for making my day bad.