This won't work on a any of our systems.

1. It assumes a connection to the localhost mongo database
2. It assumes that it knows what the mongo database and collection names are (which are configurable in modulestore)
3. It assumes the old mongo storage modulestore, so it'll break when we move to the newer split mongo database.

Most of these problems could be solved by moving the deletion functionality into the modulestore api, rather than using mongo directly.