To build on what Dave has stated;
If you wish to go down the Windows 7 path, you will need to purchase a copy of Windows7 with a COA and valid, unused product key to install Windows 7.
Make sure you create your HP Recovery Discs or USB Flash Recovery media before modifying or changing ANYTHING.
HP doesn't recommend the installation of Windows 7 on your HP Pavilion 23-b010 All-in-One Desktop Computer nor will it support the installation of Windows 7 on your computer. HP will not provide Windows 7 drivers and suitable drivers may not be available for the hardware in the computer. Also, Windows 7 may not support some of the hardware or software features designed for the computer. You will also lose the use of all "HP value added software" included with your computer.
Once Windows 7 is fully installed, we will need to locate drivers from a similar pre-Windows 8 model or you can use generic manufacturer's drivers from AMD (chipset, USB3.0, and graphics), Realtek (LAN, HD Audio, and Card Reader), and Ralink/MediaTek (WLAN).
If you have any issues or concerns, please post back.
Please send KUDOS