The previously mentioned wmic command is the way to go, as it is installed by default in recent versions of Windows.
Here is my small improvement to generalize it, by retrieving the current name from the environment:
wmic computersystem where name="%COMPUTERNAME%"
call rename name="NEW-NAME"
NOTE: The command must be given in one line, but I’ve broken it into two to make scrolling unnecessary. As @rbeede mentions you’ll have to reboot to complete the update.