I have purchased an iphone 6 plus and having icloud lock how can i remove this lock?

Contact the seller. You cannot remove the lock, the original owner is the only one that can do that. If you cannot contact the original owner, then I suggest you return the device for a refund. You will never be able to activate the device, it will be useless to you. Apple cannot help.

Hi,

if you bought from an AR you probably have a proof of purchase.

You can contact Apple support and they MIGHT be able to help you with POP.