how much does apple charge to unlock iphone6

Apple doesn’t remove carrier locks at all, so charges nothing for that. Carriers have to approve and process unlock requests for their customers. Some carriers in some countries may charge a fee for that. You will need to contact the carrier who holds the device lock about that.

If you’re referring to activation lock, then Apple will only do that for the original retail purchaser with proof of that fact. Or, in the event of an inheritance, then you would need proof of the the owner’s passing, and proof that you are now the lawful owner of their property. I am not aware of any fees for doing that.

Which lock, carrier or activation?