Booting Your Windows 10 Install USBĪs a Windows PC is booting, you may be able to interrupt the boot sequence before the Windows loader gets going by striking a function or special key on that machine. Now, you’ve got a brand-new, ready-to-use bootable USB flash drive with Windows 10 21H1 (or whatever version is current as you read this). The process concludes with a brief cleanup to get rid of temporary files and other detritus. When the MCT writes the bootable files to the drive, it tells you it’s ready.