Command line to remove an environment variable from the OS level configuration

Question

Windows has the setx command:

Description:
    Creates or modifies environment variables in the user or system
    environment.

So you can

Answer 1

You can also create a small VBScript script:

Set env = CreateObject("WScript.Shell").Environment("System")
If env(WScript.Arguments(0)) <> vbNullString Then env.Remove WScript.Arguments(0)

Then call it like %windir%\System32\cscript.exe //Nologo "script_name.vbs" FOOBAR.

The disadvantage is you need an extra script, but it does not require a reboot.