How do I delete my old phone from my car's bluetooth?

So I have a corolla 2012 le and so I hooked up my phone so that when someone calls me, I can hear them through the speakers in my car and all that. Now I just recently got a new phone and then I gave my dad my old phone. Ever since I was little, my dad wouldnt allow me to listen to the music I like in his car. I was stuck listening to the songs he liked. He told me that when I had my own car, he would let me listen to my music even if he was sitting there with me. Now the problem is that everytime my dad and I get into my car, he decides to call someone and im stuck listening to his conversation through the speakers thw whole ride. I swear he does it on purpose so he doesnt have to listen to my music. So how do I delete his phone from my car? Thanks in advance.