I don't see a way to log in to edit the wiki.  
I was going to add this simple action:
using UnityEngine;
namespace HutongGames.PlayMaker.Actions
{
    [ActionCategory(ActionCategory.GameObject)]
    [Tooltip("Destroy all children on the Game Object.")]
    public class DestroyChildren : FsmStateAction
    {
        [RequiredField]
        public FsmOwnerDefault gameObject;
        public override void Reset()
        {
            gameObject = null;
        }
        public override void OnEnter()
        {
            DoDestroyChildren(Fsm.GetOwnerDefaultTarget(gameObject));
            Finish();
        }
        static void DoDestroyChildren(GameObject go)
        {
            if (go != null)
            {
                for (int i = 0; i < go.transform.GetChildCount(); i++)
                    GameObject.Destroy(go.transform.GetChild(0).gameObject);
            }
        }
    }
}