Yeah I've gone and messed my scene up real good

I did a couple of ice-simulations each in its nówn scene files), nailed them so that my CD praised me accordingly, got a scene with a camera animation, and then merged them all together. Voila! Now my XSI scene explorer are filled with green groups that i cant delete. Did I mentioned that I also merged different revisions of the sameIce-sim several times?
This is a noob question I know, but then again I am a softimage noob, Bear with me. How can i get the greenstuff "deleteable"?