I hate to be the bearer of bad news, but this feature request has been declined.
-WarrenAnonymous supported this idea ·Anonymous commented
The leftmost "Files" tab simply creates confusion for new users - do they look there or look in the channel for relevant files? Bad setup - would like the option to remove it, and frankly "Chat" - why can't that be done in the channels or in Skype? I can put up with "Meetings" because I know that's my calendar.