Float your mouse pointer over your name in the top bar and click on logout in the popout that appears.

![enter image description here][1]

This will take you to a logout page

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The recent changes to the top bar have moved logout, it's now in the main StackExchage drop down

![enter image description here][2]


  [1]: https://i.sstatic.net/BcOYy.png
  [2]: https://i.sstatic.net/dXaVR.png