Step to remove completely a file and its histories from git

remove-file-history-from-git

1. Delete file from git repository
1. Download bfg.jar from http://rtyley.github.io/bfg-repo-cleaner/
2. mirror clone the project
    $ git clone --mirror git://example.com/my-repo.git
3. Run 
    $ java -jar bfg.jar --delete-files fileToDelete  my-repo.git
4. Update 
    $ cd my-repo.git
    $ git reflog expire --expire=now --all && git gc --prune=now --aggressive
5. Finally, push it back up : 
    $ git push