Unable to unbind ERI-K108-P8.

[Miclaire41]

I posted about a couple of months ago here
Which read as:

This device (ERI-K108-P8) was originally added to a guest account on the hik app.

Now I cannot unbind it from the account using SADP, the web interface, and the NVR GUI. the current firmware is V3.4.100 build 190222, so I am not sure if there is an update for it, but there is nothing I found on the hikvision website.
I have tried updating the firmware using IVMS 4200, but that didn't work either. So is there any way to unbind this NVR or should I just portforward my NVR instead.

I contacted HIKVISION support and I got these responses:
The unit is on the latest firmware.
The current account holder is a visitor account (They gave me the username aswell)
The only other information they gave me is when it was added to HikConnect

Is there anyway I can unbind this device? How can I get access to this visitor account or delete the account?