Late versions of DOS had deltree (delete a directory tree), newer windows do not.
RD can however delete a full tree with the /S switch:
C:\> rd C:\somedir /s
Use /Q to skip confirmation.
The stronger versions of Windows (like Vista and Seven) might require administrator privileges.
Quick way to run a console as administrator:
Type cmd in Start menu's search box, right click cmd.exe and select “Run as Administrator”
Note: the runas /user:Administrator cmd command might also be used but it will request the administrator password