iCloud Locked Help!

Hello! I have received a iPhone 5c for free and it had an iCloud account with an activation lock. The original owner was already contacted and she/he (safety) said that they have forgotten their login info to deactivate Find My iPhone and to sign out which is the major problem. When I attempted to do a factory reset (iTunes) it wiped out the content but I managed to bypass the iCloud setup by skipping it but I would like to add my own iCloud account that is already setup. Are there any ways I am able to completely remove the iCloud account without the password? (unavailability)

Thank You and have a nice Day!