how do i erase all my partitions on my macbook air and reinstall my os

[iMore Question]

i need to completly erase my hard drive and reinstall my os

 

[Just_Me_D]

Do you have an install usb disk? If so, that is all you need. Anyway, check out the information via the following link.

https://support.apple.com/en-us/HT204904