And you need `cd /d` to switch drives. This was how I rendered a Windows computer non-bootable for the first time. Ran Command Prompt as admin (because I was logged in as a user that didn’t have write access to D:\backups), and it starts in a rather important directory, then:

  C:\WINDOWS\system32>cd D:\backups\some-huge-directory
  C:\WINDOWS\system32>del /s *

Oops. I learned to look twice before running a big dangerous command. And to use /d.