Removes the property named <prop-name> from the given <object> and all of its descendants. If <object> is not valid, then E_INVARG is raised. If the programmer does not have write permission on <object>, then E_PERM is raised. If <object> does not directly define a property named <prop-name> (as opposed to inheriting one from its parent), then `E_PROPNF' is raised.