This morning's Call of Duty: Modern Warfare and Warzone update adds mode-specific uninstall options on PC, and using it I was able to get the game's install footprint down to 168GB.
After downloading the ~20GB patch, Call of Duty: Modern Warfare and Warzone weighed in at a whopping 231GB on PC.
Within Battle.net is a basic mode-specific uninstall manager that lets you ditch the campaign, multiplayer and / or spec ops. Warzone, however, is required and cannot be uninstalled, which is annoying if you just want to play Modern Warfare.