How to take iCloud off am iPhone 5c? IOS 9.2?

I just bought an iPhone 5c from someone online, and she didn't clear out the iCloud. I texted her and asked if she could take it off or whatever so I can put my account on it, it's been a few days since she said she d get to it and hasn't responded to my texts, leaving me to think she just isn't going to help. Sadly, I can't get anything like a receipt I guess to prove I bought the phone from her to go to an Apple Store. So can anyone help me?

Settings

If the seller won't co-operate with you and reset the iPhone completely to delete her iPhone account then it's permanently useless to you.

if you bought it via eBay or elsewhere using Paypal then you can apply to eBay or Paypal for a refund.

If the seller refuses to cooperate then you have to suspect that you handed over your payment and got a stolen iPhone. If that's the case then ideally you need to let police know but you then end up with no refund and no iPhone.

You don't, they have to wipe it first. You should have checked it before paying.

Apple won't help you, its a security issue so I'm not sure why you think they would get involved.