I am trying to have Mercurial forget a file, and all the history of that file. I have been tracking some binary files that have been changing a lot, and so my .hg/store/data folder now consists of 660MB of data that I don't want to keep pushing around.
I have considered just starting a new repository, but then I would lose all my code changes, so I have dismissed this.
You can't change that kind of history directly. Remember that most revision control software is usually designed specifically to prevent this.
If you insist, you might be able to do some cherry picking to create a new repository out of the old one, selecting specific changesets to reflect the history you want to reveal.
http://stackoverflow.com/questions/3558365/mercurial-removing-files-history/3558892#3558892 has exactly what I am looking for, next time I'll use that search box!