Also it's possible, perhaps within time limits, to 'unlike' any comment you 'liked' by simply clicking on the star-icon, yet again. 

IF one makes a mistake & clicks their own -- or reconsiders a position on an opinion -- just 'click on it' again. Not sure when or if that feature times out.

The ability to perform edits has been improved, as of a few weeks ago. 
Oh joy! ;)