To untrack a single file that has already been added/initialized to your repository, i.e., stop tracking the file but not delete it from your system use: git rm --cached filename

To untrack every file that is now in your .gitignore:

First commit any outstanding code changes, and then, run this command:

$ git rm -r --cached .

This removes any changed files from the index(staging area), then just run:

$ git add .

Commit it:

$ git commit -m ".gitignore is now working"

*Note :- Be sure to merge your branches back to master or move your pointer otherwise you might lose your branch