I need help with activation lock. Previous owner is deceased.

Here is apple’s official stance on deceased persons’ devices

How to request access to a deceased family member's Apple accounts - Apple Support

That is to access data ON the device. You may wish to go into an apple store and discuss what they may be willing to do to wipe the device with no access to the data on it.

You'd need to take the device to an Apple Store with proof of ownership, a death certificate and photo ID. Then they may be able to help you. Otherwise it is useless to you.