Today, Google rolled out an update for Chrome that allows you to clear out all extensions and revert your installation back to its initial state without messing up your themes, bookmarks or apps.
To access the new option, go to your settings via the menu and select "Show advanced settings". At the bottom of the page, click "Reset browser settings" (as shown above) and Chrome will clean out your installation and make it just like new. The new update also brings some improvements to the omnibox.
Smarter omnibox suggestions for all [Google Chrome Blog]