In my opinion you are on a protocol 1, and it can't be unbinded anymore. You need to search for hik-connect account where it's added.
"due to security reason, for device which add to EZVIZ cloud, we stop the self-unbind for the device, which protocol is V1.7, for device which protocol is V2.0, customer could still unbind by himself.
2、 How to determine whether the access protocol of the device is 1.7 or 2.0?
Ø Back-end devices:
NVR:GUI4.0 from V4.1.60,GUI3.0 latest from V3.4.111, update the access protocol to 2.0
DVR:From GUI 4.0,the access protocol update to 2.0
Ø Front-end devices:
Since the version of 2018-2019, the device access protocol has been upgraded to 2.0
Ø Access control intercom:
The access protocol of the second-generation intercom equipment is 2.0