Formatting a hard drive along with the install of a new OS is the best option. The vast majority of operating system installations provide a "format" option as part of the installation process.

When you’re troubleshooting your computer or installing a new operating system, you may need to “boot from a disc” or USB device (like an external hard drive or flash drive). Here’s what that ...

PSA: for MOST use cases there is now a much easier solution. If your primary goal is just to download updates faster/not use up your limited data budget, and you have multiple Macs (otherwise why do ...