Here you have it (see attachment).
With this you can select several GameObjects within one action. If one of the GameObjects doesn't have any NGUI component, it gets destroyed normally, so you can use this action for all of your destructible needs
Optionally repositions afterwards or only destroy the children of the specified GameObjects.
Tested it with several scenarios, but if you find any bugs or wish for different/additional functionalities, let me know.
I also have created more custom NGUI actions which you can find here:
http://hutonggames.com/playmakerforum/index.php?topic=15458.0Including NGUIToolsAddChildAdvanced, with which you can set the name, position, rotation and scale of your freshly created instance immediately in the same action; that I find to be very helpful.
Keep in mind that there is also a "Request Action" section in this forum, just saying