I went into a Verizon store and purchased an iphone 5 64gb. Paid for what I thought was a new phone. When it came it had some random yahoo.com account set up as the apple id. Apple has changied it to my apple id, however, I am concerned about privacy and using icloud. Apple rep told me I had to delete the other id, but it oesn't give me that option when I follow the directions given. Have been with verizon a long time 10+ years. getting REALLY fed up. Verizon tech wouldn't even talk to me, just transferred me to apple.
All you needed to do was restore the device. That would wipe all of the data on the phone and allow you to set it up as new. What probably happened is that someone purchased and returned the device. Or if you want to you can return to the VZW store you purchased it from and tell them that you were given a device that had been previously used and you want a new, unopened device. Check the device in the store to ensure that it was not used. Another possibility could be that the rep that activated your device in the store may have used a Yahoo account to initially set it up (may not be the case at all...just guessing).