Hi,
Sounds very twisted
I think you need to cut down the problem into smaller more obvious cases.
-- Being able to trigger a given animation on an object
using the action "play animation" you simply select one of the defined animation on the gameObject and done
-- Being able to randomise the animation selection
Using the "Select random String" action, you define there all the different possible animation, store it in a strin variable and inject it in the "Play animation" mentionned above
-- how to hide object
Hiding object can be done by destroying them using "Destroy Object" or "destroy Self" for example.
You can also hide object by moving it outside the camera view or switching it's layer using "set Layer" prior having set the camera to ignore that particular layer when rendering.
Does all the of the things above are fine with you? maybe you have a problem elsewhere as to how to combine them actions together?
bye,
Jean