Thanks for using Apple Support Communities. The previous owner will need to remove the device from his account by following these instructions:
Thanks for your reply and the update. In the previous article, there are instructions where he can remove the device from his account without providing his password that may be a better option for him:
If the previous owner is not present
Contact them and ask them to follow these steps to remove the device from their account:
- Sign in to their iCloud account at www.icloud.com/find.
- Choose the device from their Find My iPhone device list by clicking All Devices and selecting the correct device.
- Click "Remove from Account" to remove the device from the account.
After the device has been removed from the previous owner’s account, turn it off by pressing and holding the Sleep/Wake button located on the top right side of the device. Then restart your device and proceed with device setup as you would normally.
If that section doesn't help, then you may find more information by using another one of Apple's support resources: