How to setup www domain but show the domain without www in address bar

I have setup www.typeocaml.com and typeocaml.com both working.

But what I want is that if a user type www.typeocaml.com in the address bar, browser loads the website, but display typeocaml.com.

It is like dropbox: if you type dropbox.com, it shows www.dropbox.com in the address bar while loading. I just want the other way around.

How can I do that? I don't know anything about A record or CNAME record. Just need a quick way to achieve that.