Can I sell my iPhone to someone else?

I recently purchased the iPhone 5c from sprint and the owner of the account closet account so I'm left with just the phone. Can I sell this phone to someone or do I have to return it to the sprint store?

You can keep the phone. However just make sure that the phone has a clean ESN number. If the owner closed the account and didn't not pay the entire balance on the account then the phones on the account might have a bad ESN. A bad ESN means that the cell phone can no longer be activated again. If you gave or sold that cell phone to another person, he or she can't activate that phone. A good ESN number means that cell phone can be activated again since you on the account and if the owner paid the entire balance on the account.

So I would contact Sprint first and asked to check to see if your cell phone has a good ESN number or bad ESN number.