Allow, deny sources accessing my website (mydomain.com)

I want somehow to:

allow only.my.pyblic.ip;
deny all;

What is the best way? Does erpnext offer any option without playing with nginx configurations?
I am totally new to nginx, so how exactly should I do that?.

thx in advance

@gouz, by design, in the creation of a user, you can restrict the access of the user, with a specific IP, it dont will disable the access to the website, and I think that if exactly it that do you need do, maybe it is a post for a forum of nginx or is a time, to you check the nginx documentation here http://nginx.org/en/docs/