Firstly, ill suggest you don't remove ADW. because if you install Go launcher and something goes wrong or some file becomes corrupt, you'll be without a launcher. Always a good practice to keep two launchers. you can install go launcher besides ADW and use any one. it won't slow down your phone or anything.I don't care that much about the launcher. I use ADW because i find it faster. install the one you like better in terms of looks, speed and functionality. theme chooser has nothing to do with the launcher. it themes things like the taskbar, phone pad, system apps etc. which a launcher cannot change. And why do you want to remove it. just switch to the default theme in it if you don't want to use the theme chooser.
