If the camera doesn't have a reset button (under the MicroSD
card cover), you need to generate a reset file using the SADP
software. You can then send the reset file to your supplier or
direct to Hikvision and they will return another file that
can be uploaded to complete the reset.
This article explains the process
https://connectec.uk/how-to-reset-the-password-of-a-hikvision-or-hilook-device