I cloned the repo at https://github.com/railstutorial/sample_app_rails_4 and made a lot of changes to it (I used it as a starting point for my own app), and now I would like to
I had a similar situation, but in my case what I just needed to do was, as suggested, but with https, like this:
$ git remote set-url origin https://github.com/YOU/YOUR_REPO