When you're running postgresql there shouldn't be a problem doing
$ createdb myoacs46
Checkout or unpack oacs-4-6 files in /web/myoacs46 or whereever you usually put your web projects, configure your existing aolserver installation to use the myoacs46 db and point its documentroot to /web/myoacs46, and from there on you should be able to install from scratch.
No need to reformat your linux hard drive, please don't blackmail us with such horrible threats 😉.