If you have files on the drive you want to keep, you can shrink the volume to create a small 8GB partition.
Installing Windows 10 from an external hard drive is entirely feasible using Rufus, the Windows Media Creation Tool (with manual steps), or DiskPart. The key success factors are: install windows 10 from external hard drive
Now move to the computer where you want to install Windows. If you have files on the drive you
Installing Windows 10 from an external hard drive (HDD) or solid-state drive (SSD) is a practical solution when you lack a standard USB flash drive or need to perform a clean install on a machine with a failing internal drive. install windows 10 from external hard drive