Remove unwanted file that has been committed several commits ago from git repository

Recently I have been developing a contacts management program and as usual I've been using git for source code management. This program stores all the contacts info in a file, say contacts.info.

Today I bumped into a problem I had never had:
I noticed I had committed contacts.info several commits ago. As you can imagine, I had no intention of making those contacts info public. I needed to delete that file from my git repository, from all the commits I've committed since I added contacts.info.

I ended up finding a very useful tool for the job: BFG-Repo-Cleaner.

If you have a similar problem, here is a step-by-step guide on how to completely remove an unwanted file that has been committed several commits ago from your git repository:

1. Download BFG-Repo-Cleaner;
2. Clone a bare copy of your repository:
• git clone --mirror https://github.com/difusal/my-repo.git
3. Delete contacts.info from all the commits:
• java -jar bfg-1.11.6.jar --delete-files contacts.info my-repo.git/
4. Push the repository to save changes:
• git push

Yes, it is just that simple! If you browse through your past commits, any trace of contacts.info should now have been completely deleted.