Channel Management

Workspace owners and admins can manage all channels, except personal ones (“My private channel”).

Access Channel Management

To get started, click your team logo in the top-left, go to Settings and choose Channel management.
You'll see the list of existing channels, including the ones that have not been shared with you.
You'll see their names, their relative creation date, your role in the channel, as well as the last time there was activity in it.
You can click the header of either column to sort the list by name or activity.
To find a channel quickly, you can use the search bar at the top of the page.
Tip: Consider deleting or archiving channels with no activity in the past year.

Manage Channel Creation Permissions

In the top right, a dropdown menu allows you choose the role required to be able to create new channels. This can also be managed in the Security section:  Advanced Settings (Security) 
By default, any member of the workspace can create new channels in the workspace.
You can upgrade to  Premium or Enterprise  to restrict channel creation to workspace owners and admins only.

Manage Channels

To manage a channel, click the three-dot menu to the right of its details. You'll have the option to delete it or open its settings.
If you click Open settings you will be redirected to the Share menu of the channel. From there you can manage who has access to it, and with which permissions.
If a channel admin leaves the company, you can use this workflow to temporarily reassign ownership to yourself, until someone else takes over its management.