If the headset was registered to someone else - I’d just return them and get from legit source, because it’s not possible to transfer the headset to new owner.
I understand that you ordered the headphones, but they appear to be registered or signed under another user’s account. No worries, let me check it for you. Please send me a private message together with your device's serial number so I can check its details here in our system and assist you further. Thank you!