Wipe iMac and Reload OS X Yosemite

[Noble Bell]

I want to wipe my iMac clean and reload. I have an older iMac from mid 2007. It came with Leopard and I have upgraded to Snow Leopard, Lion, and now to Yosemite. What is the easiest way to do this without having to start with Leopard, then install Snow Leopard, etc. ? Lion and Yosemite where installed from the Mac store. I only have dvd's for Leopard and Snow Leopard.

Thoughts?

 

[doynton]

Download Yosemite and create a bootable USB (You'll need a 8GB or bigger USB stick). Make sure iLife and iWork are registered in the store before re-installing or you'll not be able to download them again.

http://osxdaily.com/2014/10/16/make-os-x-yosemite-boot-install-drive/