I've found an icloud locked iPhone, how can I return it to the owner?
If the SIM card is deactivated, replace the SIM card with one that is functional and will provide the device with a data connection. This will allow the phone to communicate its location to Find My iPhone which the original owner can use to locate the device.

You can't restore a device with an active Activation Lock (except DFU and that just puts it back in Activation Lock), so “wiping the phone” isn't a possible avenue.