Mercurial undo last commit

Question

How can I undo my last accidentally commited (not pushed) change in Mercurial?

If possible, a way to do so with TortoiseHg would be prefered.

Update<

Answer 1

hg rollback is what you want.

In TortoiseHg, the hg rollback is accomplished in the commit dialog. Open the commit dialog and select "Undo".