So tagging on to this question since @Juan Carlos González Martín answer will likely prompt user to recreate a Channel. Is there an easy way to move the contents of one Channel to another, aside from downloading the docs and reuploading?
Unfortunately no. You can use Move to / Copy to inside of Teams to move files from one channel to another, but that's all you can do. Conversations are not currently able to be moved within Teams. There may be 3rd party tools that could move conversations but they won't look as they did from the source channel since they cannot impersonate users to post the chat's on their behalf / update dates etc.