On occasion the content structure may need a revamp, and channels can be permanently deleted if needed. *However, you are not able to permanently delete a channel if it still contains stories.
Often times, channels are 'unlinked' but not removed completely so they still exist in the system although they will not display on the front end of the structure.
If a channel is not permanently deleted, when adding a new channel, you may get an error that the channel name already exists and they system will not let you proceed. It's likely this channel existed and was unlinked rather than deleted at some point. To search, select "Add existing Channel" and type the channel name you are searching. If it's located you can add this channel back to the Hub. And then add the relevant groups to the channel as well.
If this previous channel should be deleted completely, add it back, archive it's stories and then proceed to delete