New apple ID

See if they can recover the ID/password.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

Enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage            

Apple ID – Forgot Password            

If you create/use a new Apple ID, you will lose access to some of your data and the purchases made with your existing Apple ID.

Apple ID - create a new.      

Apple ID – Create        

Apple ID - Could Not Create or Could Not Set Up iCloud message.    

Your friend either needs to remember their Apple ID to remove it from the iPhone or you take the iPhone to Apple with the original invoice so they can help you unlock it and remove your friend's Apple ID. This only works if the invoice you have us from Apple or an authorized Apple reseller.

Apple won't give you a new Apple ID, you can simpy use whatever Apple ID you yourself have. Or create a new one yourself if you really need one.