Found under DESCRIPTION, you can set a VOD file, live stream, package or playlist to off like so:
Doing so will make the video inaccessible and, if the content was monetized, will disable the paywall preventing future people from buying the content.
To make it clear, in the case of live channels, the stream will not automatically turn back on again once you start to stream though the encoder. You will have to go back into DESCRIPTION and manually turn it on again before this will happen. If you stream often and have a free stream, it's recommended just to leave the channel on to make it easy to begin streaming again during your event or programming.