Unless they really were not listened to. But I generally like to keep all my albums, even if I haven't listened to them for ages, because one day I'll just get the urge to listen again.
Like, I hadn't listened to 'Rumours' for ages, but suddenly it was a really sunny day recently and I put it on and loved it.
I don't delete songs. For a song to even MAKE it into my Itunes library I have to love it. And besides, even if I haven't listened to it in a while I still love it. And it helps to have a diverse musical library anyway.
I can never delete stuff, unless I suddenly start to really hate an artist. But I still own music that I listened to in 2007-2009 that I'm ashamed to even own now. I used to download entire discographies when I'd get into an artist, and now own hundreds of albums that I never listen to.
I'm such a mess when it comes to delete music... I bought to HDD one is for my music and stuff and the other one is for my perfonal files... My iTunes purchase can take the play it wants on my computer as long I still have enough space to play a little bit of Sims.