The proper way to install windows 7 would be to completely wipe the hard drive, then you lose a lot of drivers because they are specifically for windows 8. You can if you know what you are doing, but it would be best to wipe the hard drive and re-partition it manually and make a back up partition with the drivers and the OS on it. Windows 8 says you can downgrade to windows 7, but downgrading often causes problems.
I have a 2 year old slimline s5, and its great, except HP doesnt want to include HDMI, because of that and slow video play back Im giving it away to a friend, its an upgrade to him, AND it has Windows 7, a great plus,, I wouldnt call getting rid of windows HATE and loading windows 7 a " down grade", Id say do it as soon as possible, and get rid of the norton anti virus before its activated,,, other than those issues its been a very good pc. Oh hp lacks the ability to raise the ram from 4 to 6 or more, thats why Lenovo and Acer is kicking their butts.
I believe I had seen that option in the online guide.
I was going to reinstall Windows 7 but my friend told me of some software by Stardock.com that made this machine very user friendly. Good luck.
This HP PC is warranted as configured. This HP PC has Microsoft Windows 8 operating system. I recommend contacting Microsoft for any downgrade possibilities.