Buying used iPhone5c - need to know about iCloud I am supposed to buy the phone off someone. She says she does not have the iCloud email, but has the password (she says it was her ex's).. She told me there is something online that I could do to get the old iCloud credential off and use mine. 

If that's not possible... The password does work for the email on the phone. 
Would I be able to use it for getting online, downloading apps and such? Any major things I would not be able to do with it? 

Thanks in advance!!
There are two possible scenarios:


The device is up and running, and you can unlock it with the four digit code. If that's the case go to Settings -> iCloud and choose logout at the bottom of the page. Then you only need the password of the account.
The device was restored to factory settings. In this case activation lock would be active and you need to know the AppleID and the matching password. If you don't know these you need the original receipt and an appointment at your Apple Store to unlock it. The receipt needs to contain your name, otherwise you need help from the person whose name is on the receipt.