Your class is a handle class. As stated in the "Handle Class Methods" section of this documentation page that means you inherit a dozen methods.
For all those methods except isvalid you could "extend" it as shown on this documentation page in a methods block with the Hidden attribute and I believe that would allow them to still work while removing them from tab completion. The isvalid method is different, it is Sealed so you can't override it with a Hidden method in your subclass.
Another possibility, if your class doesn't need to be a handle class, would be to remove that superclass from your class's definition.
