Mixed iphone apple id accounts...!

Hey!
I am 15 years old, so that means i just got my own Apple id & Icloud... Before this, i used my dad's account to pay apps and music and so on.
The problem is now that when i log on to he's account it shows all my contacts and more! (although i'm logged in to my own account on my iphone) And it must be said that i got an iphone before him... So he used he's account on he's computer, and i think that's why its MY contacts and not he's?!....

So how do i delete my iphone from he's accounts? So it only uses mine??
Please help it's actually a big problem, because then he can't see all his stuff :/