How do I remove my iphone from itunes

Ios 6 destroyed my ability to connect to wifi on my Iphone 4s. I bought an android phone because Apple will not assume any responsibility for the download corrupting my phone. Now I can't receive text messages from my iphone friends because their phones think I still have an iphone and are sending me imessages. I just want the new phone to receive text messages from my friends with iphones. How do I remove my phone from itunes so my android can receive text messages from my friends?