remove file history from git

git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch path_to_file" HEAD

$ git rm --cached giant_file
# Stage our giant file for removal, but leave it on disk

To replace all text listed in passwords.txt wherever it can be found in your repository's history, run:
bfg --delete-files YOUR-FILE-WITH-SENSITIVE-DATA

The BFG Repo-Cleaner is a faster, simpler alternative to git filter-branch for removing unwanted data. For example, to remove your file with sensitive data and leave your latest commit untouched), run:
bfg --replace-text passwords.txt