Remove a file from a Git repository but keep in a local file system

To remove a file from a Git repository but keep in a local file system, do as follows:

git rm --cached some_project.iml

git commit

You can `git push` if needed.

Reference:
http://stackoverflow.com/questions/1143796/remove-a-file-from-a-git-repository-without-deleting-it-from-the-local-filesyste