def delete(self, retarget_to=None, author=None):
        with self.env.db_transaction as db:
            self.env.log.info("Deleting milestone %s", self.name)
            db("DELETE FROM milestone WHERE name=%s", (self.name,))
            Attachment.delete_all(self.env, self.realm, self.name)
            # Don't translate ticket comment (comment:40:ticket:5658)
            self.move_tickets(retarget_to, author, "Milestone deleted")
            self._old['name'] = None
            del self.cache.milestones
            TicketSystem(self.env).reset_ticket_fields()

        for listener in TicketSystem(self.env).milestone_change_listeners:
            listener.milestone_deleted(self)
Delete the milestone.
dataset/ETHPy150Open edgewall/trac/trac/ticket/model.py/Milestone.delete