Permanently Deleting Application

Hey guys and gals,

I need a bit of help over here. I recently downloaded the trial of "Boom" by GlobalDelight. For those of you who don't know, its a program that is supposed to boost the output volume of your mac. Anyway, I didn't care for it so I deleted it, or so I thought. I noticed when I select audio outputs it still shows "boom audio device" as an option. I know I need to go into the preferences or something to remove it but I cant seem to find it. Does anyone have any suggestion as to where I should look, or where it may be in my library? Its kind of annoying, and I'd like to get rid of it. Any help is appreciated.