Removing User names in login screen

So hi guys, currently i m running on a mac with yosemite. To maximise my mac's security, i would like to remove the user name in login screen, which is, i will have to type in my user name as well when logging in.

I discovered that there is a option called "Username and password" in the login options menu. I selected it instead of "list of users" but it effects only when i log out. When I boot my computer, my user name remains and only requires me to type in the password.

What can i do or set in order to have the screen requires my username as well? Thanks:)