Hi,
Vizard objects are not deleted unless you explicitly delete them. So when your custom class is deleted you need to manually delete all the Vizard objects it contains. When you create a python class you can override a function which will be called when the object is deleted. Example:
Code:
class MyObject:
def __del__(self):
#This is called when the object is deleted
self.node.remove()
self.fGravityArrow.remove()