Removing child problem

I have a bunch of objects in a movieclip.
Why am I not allowed to do the following?

rubyCont.getChildAt(i).Destroy();

Destroy() is a function of the child in rubyCont. The child is mc_Ruby.
Obvious if I do mc_Ruby.Destroy(); all the instances get destroyed.
I don’t see why I can’t do this? I’d like to remove the objects with that function so that the eventlisteners also get removed…

Can someone give me a quick explanation/solution?
Thanks!

~Mr Flopsie