I couldn’t not find the owner to unlock the activation what should I do

If you can't contact the owner directly, if you bought it through a third party such as eBay, contact the third party for a refund as the device is useless. There is no known way to bypass activation lock.

Turn off Find My iPhone Activation Lock - Apple Support

Hello!

I absolutely understand that is not a good place to be in.

The only way to unlock the iPhone is either the owner will have to remove that Activation lock or you will need the original purchase receipt to request Apple to remove.

Reaching back out to owner would be the best option.

If that is not possible, I would look into possibly contact local authorities to report and/or if purchased with a major credit card, you may want to contact them directly to see if there is some sort of buyer protection. Same if you purchased from a selling site such as Amazon, eBay, etc.

Turn off Find My iPhone Activation Lock

You are correct.

OP, read this link because your device is useless. You cannot bypass activation lock and you are just another buyer who has been duped, likely by purchasing a stolen device. If you can't get your money, recycle the phone. Apple will NOT help you. We CANNOT help you.

This link explains: The All Too Common SAD Reality of Buying … - Apple Community

brittier8 wrote:

The only way to unlock the iPhone is either the owner will have to remove that Activation lock or you will need the original purchase receipt to request Apple to remove.

Please note that Apple will only remove the lock for the original owner (if then), not for a subsequent owner who happens to also have the purchase documents.

brittier8 wrote:

Apple supports the device. Original proof of purchase proves ownership.

That is not what we have been given to understand. It's apparently neccessary to provide the device, the original purchase documents and some ID to prove you are the original owner. The only exception is when the original owner is deceased, when a copy of the death certificate and proof that you are now the legal owner is apparently also necessary.

Apple supports the device. Original proof of purchase proves ownership.

For more questions on this please Contact Apple Support directly.

Unfortunately you can do nothing.

That device, without knowing the credentials that were used by the previous owner, is useless to you.

Regards

Giulio

Recycle it.