untrack all files git code example
Example 1: git ignore still tracking
git rm --cached <file>
git rm -r --cached <folder>
Example 2: github untrack files
git rm -r --cached .
Example 3: remove gitignore files
git ls-files --ignored --exclude-standard -z | xargs -0 git rm --cached
git commit -am "Remove ignored files"
// answer from: thSoft