How do I unlock an iPhone Locked to Owner?

The only way to unlock such an iPhone is with the credentials of that owner. If it’s not you and you cannot contact the owner for help then you will never be able to use that iPhone. Activation Lock is a theft deterrent that cannot be bypassed or worked around.

How to remove Activation Lock - Apple Support

On the the other hand if the owner is you and you have forgotten your Apple Account ID or Password then follow the instructions in the inks below.

If you forgot your Apple Account primary email address or phone number - Apple Support

If you forgot your Apple Account password - Apple Support

If you forgot your iPhone passcode or your iPhone is disabled - Apple Support

There are more than one way to unlock such an iPhone.

If you see a "Locked To Owner" message, one referring to iCloud locked, or activation locked:

Read this article about removing Activation Lock --> How to remove Activation Lock - Apple Support Unless you have the account information that set the lock, or the original receipt from Apple or an Apple approved vendor, or can demonstrate legal inheritance from a deceased owner, you cannot remove the lock; return or recycle the device.

If it is asking for an account that is not yours, take it back to the person from whom you received it. Get them to do the things in this support article or ask for a refund --> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support There is no way to discover the owner of a device unless they left a message to display on the device when it is turned on, or the person who gave you the device knows them.

From the very bottom of Apple Trade In - Apple :

"Does Apple offer recycling?

Yes. Apple Trade In lets you recycle any Apple device (including devices from Apple-owned brands) at any Apple Store and on Apple for free. That includes your batteries and old electronic products as well as free, on-demand packaging recycling for our commercial, education, and institutional customers. When we receive your device, it will be thoroughly inspected to determine if components can be recycled or reused. Whether recycled or reused, all activities relating to the processing of your device will be managed in an environmentally responsible way."

Request to remove activation locked to owner.

venmatman wrote:

Request to remove activation locked to owner.

The answer has already been provided.