How can I remove Activation Lock on an iPhone?

Only the original owner may remove Activation Lock.

How to remove Activation Lock - Apple Support

Where did you get this iPhone? To remove Activation Lock, you need the original owner to unlock it with their Apple ID, or provide Apple with the proof of purchase receipt.

If you bought this iPhone from a third-party seller or site, it’s likely that you have been scammed with an Activation Locked iPhone. Next time, consider purchasing from Apple or an Apple-authorized retailer.

⇢ How to remove Activation Lock - Apple Support

-Zachyy

The All Too Common SAD Reality of Buying a Used iPad/iPhone – Apple Community