Use a tool like Parted Magic (paid) or boot a Linux USB and run:
(Replace /dev/sda with your drive)
| Your Goal | Next Step | |-----------|------------| | Install Linux | Boot from your Linux USB and select "Install" | | Install a fresh Windows | Boot from your Windows USB and click Next on the unallocated space | | Sell the PC | Leave the drive empty. The buyer will install their own OS | | Recycle the PC | Remove the drive first. Erase or destroy it, then recycle the PC without a drive | erase windows
This guide covers all three.
An 4GB+ USB drive and a second computer. Use a tool like Parted Magic (paid) or
: Use a tool like Rufus to put your new OS on a USB stick. An 4GB+ USB drive and a second computer