You can find Message Channels Settings in the Settings > Message Channels (under CONFIGURE). From here, you can create, edit and disable (except the default channel) message channels.
Use the “Edit” option (appears on hovering) near a Message Channel to change any of the settings for that Message Channel like the name, welcome message (default message in the message channels when a user selects the message channel), the icon to use, group to map to conversations in this message channel, and tags associated with it.
Welcome Message: The “Welcome Message” can be used to set context and expectation with the user.
Tags: Tags are used to display a subset of message channels (based on user-type or context).
Public vs. Private Message Channels: The private/public option is used to determine if a generic “launch channels” method should include the message channel (public) or not (private).
To add a new channel, use the “Add channel” option at the top right of the Message Channel settings.
To disable or enable a channel, simply use the toggle on the right side of it. You cannot disable the default channel, though you can rename/edit it.
To re-order message channels, first, hover on the channel for the positioning control to appear on the left as shown in the image above. Then click on it and drag up/down to change the position of the channel.