Show or hide teams or channels
A channel must be visible to send notifications to you. Hiding a Team or channel will turn off all notifications for that Team or channel.
This is a great way to clean up your list and focus on the teams and channels you're active in.
To show a channel, click the arrow next to # hidden channels, and hover over the one you want to show. Click Show.
If you don't want a team or channel to show in your teams list, you can hide it. Go to a team or channel name and select More options 
> Hide.
You can also look at a channel without having it shown constantly, just click on it and don't click "Show." It will be italicized and will return to being hidden after you click a different channel in the team.
