[description]

To remove an entry from the index, use a command like this:

    git update-index --force-remove <file>

Remove all entries from the index!

[setup]

echo "file 1" > file1
echo "file 2" > file2
echo "file 3" > file3
git add .

[setup goal]

echo "file 1" > file1
echo "file 2" > file2
echo "file 3" > file3
git add .

git update-index --force-remove file1
git update-index --force-remove file2
git update-index --force-remove file3

[win]

test "$(git ls-files | wc -l)" -eq 0