EventLive has a built-in option for trimming video (only from the beginning). To use this option:
1. Open EventLive app or Broadcaster console
2. Open your event
3. Click Manage Video tab
4. Go to Trim Video section
5. Enter start time in hh:mm:ss format if you want to clip the beginning of the video. For example, if you want to start the video 20 minutes into the live stream, enter "00:20:00"
The other option is to use any other movie editing software and to reupload the edited version of the video in the Manage Video tab. The edited video will replace the live stream video.