EGit and Untrack

I am struggling with untracking some files I have added to the index by mistake.
I didn't expect it is so easy to add a file to index and so difficult to remove it from there.

Related story.

My recent two commits were failed attempts to achieve only that!
Without the ability to remove files from index everything is going to complicate a lot.

It looks like the only way to remove these files is to:

• rename offending files
• commit
• rerename them back
• commit

(spossibly with updating .gitignore if needed)

If that is the only way - next two commits are going to do just that.

EDIT:
It occurred that Egit has some rm incompatibilities.
Here is the explanation
so I cannot use Egit->commit for that.
One option is to Egit mark the file as untracked (that does "git rm --cached") and then commit via shell, not via Egit.
A more elegant way is to use "Git Staging" view (Preferences->Show View->Team) to commit.