How do i remove my phone number from my mac for iMessage?

I have a macbook air and whenever i try messaging my daughter's phone who has an iphone 5, it ends up in coming back to my mac. So that means my mac is using her phone number as imessage. I tried removing it but i cannot find the setting to do so. PLEASE HELP. i want to remove her phone number from my mac as an imessage setting.