Repartition and reinstall on 2012 Air + Mavericks
The safest way to wipe your entire drive and do a clean OS install is this:


Remember to back up ALL of your data!
Open Boot Camp Assistant and select the "remove windows" option. Follow the steps to remove windows and resize your drive to only be MacOS.
After this is complete, shut down your computer.
Boot into recovery mode by holding Cmd + R at startup.
Open Disk Utility in recovery mode. Select the remaining partition (MacOS), then set a name for it in the box provided and wipe it.
After this is complete, close Disk Utility and choose the "Install Mac OS X" option.
Follow the steps to install Mac OS X on the new partition.