Wait is this a keybind for a gui or what?
You go into your options pannel (crtl-o) in game, and set the key bind.
When you set the key bind, pressing the key you set will have it open a window with a text bar and two buttons on it.
The ignore button adds the name in the text bar to the ignored names list, and the unignore button does the opposite.
The window can be closed normally or by pressing the escape button.