I am not going to bother with genres that I don't listen to... I don't listen to them, why would I need to ban them? I mean, sure, I would love to live in a world where need not worry about having rap or country forced upon me, but this only occurs on a rare level--though it was prevalent in high school, which is thankfully far gone.
However, I will go ahead and suggest banning a band and if that is off limits, then I just propose banning every song, past and present, by Nickelback. I do believe that to enjoy the band you must have some sort of mental defect, but that does not stop my local radio station (alas, I have only a radio in the car) from playing their songs over and over again.
If not, then I am going to have to go with Teen Spirit by Nirvana. Since I started listening to our local station back in 2003, I have probably heard this song a few thousand times and it is pretty much right up there with all of Matallica's Black Album for songs that get way too much f**king air time. And why am I bringing up only radio? Because there are few situations where I do not control what I am listening to, with radio being the major one and other things, like tv, movies, and friends, which are all pretty minor.