You can still play the games without steam (I often play without internet connection). But of course you'll miss out on a lot of things (multiplayer, achievements etc.) which might be important to you.
You can definitely remove it, but it's not like GOG where the launcher really is 100% optional and you can install and play the games without an internet connection or an account of any sort
For some games this is true. But there's plenty of games which have an 'offline mode' that require you to connect to an auth server before the game will launch.
