Question: Since there's no longer a taskbar/start menu Control Panel, how do you clear the history of the Run box in Windows 8?

Answer: 
You can use [CCleaner](http://www.piriform.com/ccleaner) to erase the run history.

![enter image description here](https://i.stack.imgur.com/XUiBH.png)
This did it for me

```
rundll32 inetcpl.cpl ClearMyTracksByProcess 1

```

[Clear History From the Command Line](http://howtogeek.com/howto/windows/clear-ie7-browsing-history-from-the-command-line)