@Azhar_Mahmood, chances are slim that WD will address this long standing issue any time soon if at all. Supposedly part of the reason why one cannot, within the Dashboard, set the Public Share to Private has to do with the Twonky Media Server. Which I believe uses the Public Share when it aggregates content from other media servers.
If one is using pre OS 3 firmware there was a hack that would allow one to set the Public Share but it ONLY works on pre OS 3 firmware:
https://community.wd.com/t/controlling-access-to-public-folder/92133
