4
I don't think you can change the name of the html folder. The problem is that it exists, not its name.
I think you're basically hooped if you've run the install already. During the install the directory is written to the mainpage.phop file. I moved my installation and tried to just update the two spots in the mainpage.php file and it didn't work. It blew up on me - I had to start over.
If you don't have a lot of stuff that you care about, I'd delete and start over.