My macbook air wont let me erase my disk? What the title says. I'm trying to delete all the data off my macbook air. I pressed command+r, went to disk utilities, selected my disk in the slot to the left, went to the erase tab. The "erase" button is faded so I can't click it. Format is at Mac OS Extended (Journaled) already, but it's also faded out. Almost every option is faded. What's wrong? Why won't it let me erase the disk?
You cannot erase the currently-running volume. Shut the computer down, restart while holding the option key, and choose the Recovery HD.

Find Disk Utility in the menus and you will now be able to erase your internal storage.