Erase Macbook to recycle
I am having the same problem the earlier person had: I go to disk utility after starting my MacBook in recovery mode (Command + r, hold until Apple Icon appears), go to Disk Utility, Select MacIntosh HD, and the Erase button is greyed out. Can't erase! It's a 2009 model, so I no longer have the original factory installation disks.
MacBook, 10.11