Change Apple id

 you will need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/ My Phone and erase the device, then remove it from their account. If you can’t do that, the device is useless. Apple won't unlock it.

Turn off Activation Lock - Apple Support.      

We, as a group, can't help you. We are not authorized to remove the activation lock from any device. 

And, under your circumstances, Apple support will have no justifiable reason to remove the activation lock unless a rare condition exists. Rarely, an iDevice is purchased activation locked from an authorized Apple seller. In your case is like that, then Apple support may remove the activation lock if you have your receipt for the purchase of the device with its serial number on it. If you have such a receipt, then you can use the support options below in making your case. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.

Get a call from Apple support to help solve your problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and

region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.