Firstly, your device will need to be running recent / the latest available firmware.
We have only yesterday seen the first reference to this feature in the brief notes to the latest firmware for the -I Series NVRs:
Latest HikVision Firmware for -I NVRs - new V4.1.65 (76XX, 77XX, 96XX NI-I)
e.g. it should work with -I Series NVRs running firmware V4.1.65 or newer...
Hikvision Password Reset - Do It Yourself
We have only yesterday seen the first reference to this feature in the brief notes to the latest firmware for the -I Series NVRs:
Latest HikVision Firmware for -I NVRs - new V4.1.65 (76XX, 77XX, 96XX NI-I)
e.g. it should work with -I Series NVRs running firmware V4.1.65 or newer...
Hikvision Password Reset - Do It Yourself