Under what circumstances would this be useful?

http://bugs.python.org/issue19462 asks for a 'remove_argument' method.  That seems to be most useful if the argument is inherited from a parent parser.

A subparsers argument could be inherited from a parent (I think), but the parenting mechanism does not provide a reference to the corresponding  _SubParsersAction object.  We'd have to look it up in the main parser._actions.

Also parenting does not make copies of the Actions.  It just copies references.  That means any change to the main parser  _SubParsersAction object is also a change to the parent's object.

http://bugs.python.org/issue22401 discusses the problems involved changing an inherited argument.

The method seems simple enough, but I'd like to see a better case for its value.