[mercurial] Is there any way to delete local commits in Mercurial?

Modern answer (only relevant after Mercurial 2.1):

Use Phases and mark the revision(s) that you don't want to share as secret (private). That way when you push they won't get sent.

In TortoiseHG you can right click on a commit to change its phase.

Also: You can also use the extension "rebase" to move your local commits to the head of the shared repository after you pull.