You open Command Prompt as Administrator .
diskpart list disk (find your external drive – be careful not to pick the wrong one ) select disk 2 (for example) list partition select partition 1 active exit install windows from external hard drive
In the end, you sit back, watch the “Getting files ready for installation” screen, and realize: an old external hard drive just saved you from hunting for a DVD or an 8 GB flash drive. You open Command Prompt as Administrator
First, you open and delete all partitions on the external drive. Then you create a single primary partition, format it as NTFS , and mark it as active (so the computer knows it can boot from it). you sit back