How to restart my macbook air from zero
Hey, I want to know how to restart my macbook air from zero to have space to install windows 8 since I need it for school
Thanks for your cooperation =)
MacBook Air, OS X Yosemite (10.10.5)
You don't necessarily need to do that. You can partition its storage using Disk Utility and install Windows on its own partition using Boot Camp.
Read How to install Windows using Boot Camp - Apple Support.
If you really want to erase the MacBook Air completely, follow What to do before selling or giving away your Mac - Apple Support, but as I wrote you don't need to do that.