I created a Gist on GitHub and I saw informations I don\'t want anyone to see. I updated the file since, but everybody can still access the old revision of the file.
If you are not concerned about showing any of the revisions on the gist, you can do the following to eliminate all history and just show one revision.
git clone some-gist-repo
cd some-gist-repo
git rebase -i --root $tip
You would be able to see all the commits for that gist in your editor. Just pick the first one and replace everything else with s or squash. Once done, save and add a commit message and then do a force push to master like this and you are good.
git push -f origin master
The only revision that would be visible is the addition of file(s) and thats it.