'Issue DROP ddl for this type, if applicable.'

def drop(self, bind=None, checkfirst=False):

    if (bind is None):
        bind = _bind_or_error(self)
    t = self.dialect_impl(bind.dialect)
    if ((t.__class__ is not self.__class__) and isinstance(t, SchemaType)):
        t.drop(bind=bind, checkfirst=checkfirst)
