Can't do clean system install (erase) on MacBook Air 2011
The erase function in disk utility is grayed out and I need to wipe this computer. How can I do this?
You need to erase the entire disk. Boot into Recovery Mode and choose Disk Utility. Then choose the uppermost, unindented icon representing the entire drive. (You may have to go to the upper left of Disk Utility and click on "View" to show it.)