Despite the way the question was worded, I took the question to mean: how do you clear the Roku's console output, so that each time you start a new session you get a fresh, clean console log. Irrespective of whether you're using telnet, a web browser, Windows or Macs, or any other method to view console output during debugging, every time you run a dev channel or side-load again, and connect to port 8085, you get the output from previous sessions. I've often wondered myself whether there was a way to clear that output without re-booting the Roku.