Found an iphone, i would like to sell it, how do i disconnect service from the phone?

I was walking down the street and found an iphone, i do not plan on being a good samaritan and returning it to its owner, i would like to sell it, how can i do this, service to the phone is still active?

What iphone is it?
email me

Simply remove the sim card. But that won't stop the real owner from finding it if location services are switched on and he or she uses find my phone.