Remove "Add / Remove Applications"

The easiest way would be to just disable the menu entry from "alacarte".
If you really want to remove it from your system you can just:

sudo apt-get remove gnome-app-install

Also, if you'll need at any later time a GUI app to install software, you can install, if it's not already installed on your system, synaptic:

sudo apt-get install synaptic

Synaptic is installed by default, so is aptitude. And the apt-* commands so no worries removing that gnome thingy.

Add / Remove Applications is kind of redundant. If you need a GUI installing your software there is Synaptic, otherwise you can always use aptitude from the terminal (which is what I do most of the time).

You shouldn't be hating so much on it antarta, the source package is less than 1MB in size, the installed application can't be taking up too much space. Can't you just remove it from the main menu, so you never see it's there?