Remove Classes From Array

Hello friends,
here’s another AS3 question from me that got me quite puzzled. I have a lot of classes put in an array to easily adress them. Like this:

var newClass:NewClass = new NewClass  ;
niceArray.push(newClass)

Now at one point of the program, I want to delete those classes and add them in anew without the old ones acting anymore.

I tried to simply erase the Array contents like

niceArray = []

or

niceArray[0] = null

but classes, that got a child still on screen don’t “vanish”, so I believe, also classes that have been erased from the array still “act” and therefore take up capacities and lead to bad performance if I repeat the process a few times.

Is there a safe way to get rid of classes that have been called in a program or at least stop them from acting?

Thanks!