If you want to get certainty about the usage of a channel there are currently three ways.

1. The Where-used list (In the main or context menu) can be made directly in the eBiss interface. Channels can be only referenced in Partner management, Jobs or Typesets.
2. Alternatively, a system dump can be searched for the channel name using a suitable tool (such as GrepWin or Notepad++). If you get more than one hit, you have to assume that the channel is needed¹⁾.
3. The now obsolete manual way is to search through all jobs, type sets and partners.

Note: In multi-node systems with public channels²⁾ each node must of course be dumped and evaluated individually.