That question does not belong on Stack Overflow. It is kind of silly that it got migrated two years after it was posted instead of simply closed. It looks like 4 closers (other than Michael Petrotta) chose to migrate it instead and that is unfortunate.
In cases where reverting the migration is necessary, moderators on the target site have to contact the moderators on the source site and get them to clear migration history. The question is then deleted on the site it was migrated to.
If the question happens to pick up good answers after it was migrated, we sometimes do the opposite and clear migration history on the target site and migrate the question back. The original question on the source site can then be deleted or merged with the "new" one.
Reversing migrations requires coordination between sites and occasionally gets a bit hairy. It only makes sense to do so for questions that are worth saving. In this case, ignoring the fact that the question isn't on-topic for SO, reversing the migration only to have the question closed again doesn't make a lot of sense.