Like riding a bike... when you fall down, get back up and try again, only with this, no skinned knees or elbows...
You will have to uninstall via Steam, I'm almost certain of that, prior to trying a re-install in a different directory. That's just the way they work their licensing anymore. Use the Steam control panel though, not the install routing itself, to change the directories. I'm not even sure you can do multiple copies anymore for different mod installs. We'd have to have someone with a newer Steam version come on and tell, because those with older Steam versions don't seem to be as restricted in what they do with their game.