Edit the channel permissions to control whether others can upload, share or view content (private channel). If a channel is private, only those invited to the channel (and account admins) can access the channel or its content. The Permissions option can be found under channel Settings (sprocket icon) and can be changed only by the channel owner (and account admins).
Use the list below the options to invite others or remove their access. You can also delete any sharing links you have previously sent in case they should not be used any longer.