When you want to be specific:
To remove a file
git rm --cached <file>
To remove a directory
git rm -r --cached <folder>
Otherwise:
git rm -r --cached .
Finally:
git add .
git commit -am "Remove ignored files"
When you want to be specific:
To remove a file
git rm --cached <file>
To remove a directory
git rm -r --cached <folder>
Otherwise:
git rm -r --cached .
Finally:
git add .
git commit -am "Remove ignored files"
Source: How to make it forget