E.g.
I tried to delete an old Category but can’t because the error message says a Chat Channel is connected to it (see pic).
I looked in the Chat Channels but don’t see where a Category is linked to it please?
AI-generated summary
In a support discussion titled ‘How change a Chat Channel’s category that it’s linked to’, DGForum reports being unable to delete an old category because a chat channel is linked to it, and can’t find where that link is configured. Canapin responds with step-by-step instructions: from the sidebar or chat window, click the edit channel icon, then the cog icon next to a channel, and under ‘About’, view the linked category — indicated visually by the left border color. DGForum replies that they can’t change the category — clicking it just redirects to that category. DGForum then decides to delete the channel and create a new one instead. Canapin confirms that changing a channel’s category is not possible, noting this limitation with a smiley. The thread concludes with the workaround of recreating the channel under the desired category.
Hi DGForum 
From the sidebar, click the edit Channel icon:
You’ll see the list of chat channels:
(the color on the left border gives you a hint of the category in which they belong)
Click the cog icon of a channel: 
Click on About, and you’ll see to which category the channel is linked:
Thank-you.
But it won’t allow me to change it to the new Category.
When I click on it it just redirects me to that category.
We’re just deleting it and making a new channel thank-you.
Indeed, you can’t change a channel’s category.