I am trying to delete everything off my MacBook book air and there is no delete button when I go to system preferences or general. Mine is an older air
where is delete everything on an older MacBook air
MacBook Air 13″, OS X 10.10
Question marked as
There isn't one because you cannot delete or erase the OS you are booted into. You need to boot into recovery by holding the command and R keys while booting up. It will take a while. From there you can erase and reinstall the OS.