To set up a public channel on Slack: Click on the ‘+’ button next to Channels Toggle the switch to Public Channel. A word of caution though - anyone on your team can view and join a public channel Enter a channel name which can be 21 chars long Add a channel purpose and select members to inviteHow do you leave a Slack channel?
Leaving a Channel Open Slack's website. Click "Sign in" at the bottom of the page. Enter your team's name, then click "Continue". Click or tap on the channel you wish to leave. Click on the gear symbol to open the Channel Settings menu. Click the "leave #[channel name]" option to leave the channel.