Here's the procedure, relevant if you're using the Chrome web browser.
1 - Right click anywhere on the Karbon page and select "Inspect". A debug panel will open.
2 - Half way down the debug panel there should be a console tab
3 - In the console tab type: window.localStorage.clear()
4 - The response should be “undefined”
5 - Close the browser, then reopen Karbon and the colleague should no longer display