It looks like you were interacting with
I'm the Riddle_Decipher & I'm at your service.
I understand you've attempted to remove the LogMeIn using the Revo uninstaller and yet can't find the application,
That said, the app should normally delete on its own when the PC is restarted after the Chat support interaction and hence I request you to restart the computer if you haven't already 
That said, if the issue is regarding the annoying pop-up each time you turn on your PC,
You can disable the pop-up using the System Configuration Utility: Click here for details.(look under Services tab of the MSConfig window).
Keep me posted for further assistance