Undoing add in Git

If you add a file to staging area and want to undo the action, use below command :

# Undo add action for a file
# --, the following parameter will be parsed as a file path
$ git reset HEAD -- <file-path>

# Examples:

# Undo add action for index.php
$ git reset -- index.php

If you want to undo add action for all files added to staging area :

$ git reset HEAD

If fact, git status tells you how to unstage a file :

$ git add index.php
$ git status
On branch master
Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)

    modified:    index.php