Delte server header form response

Env :- Rails 3.2 , Ruby-2.1.1p76

Server: nginx/1.8.0 + Phusion Passenger 4.0.59
X-Powered-By: Phusion Passenger 4.0.59

I want to remove these 2 headers from response. I know I can edit my nginx config and set server_tokens to off but is there any way I can handle this in codebase?