リファレンス、WshEnvironment オブジェクト、Remove メソッド
まんま
Dim WshShell, WshEnv Set WshShell = WScript.CreateObject("WScript.Shell") Set WshEnv = WshShell.Environment("PROCESS") WshEnv("TestVar") = "Windows Script Host" WScript.Echo WshShell.ExpandEnvironmentStrings("The value of the test variable is: '%TestVar%'") WshEnv.Remove "TestVar" WScript.Echo WshShell.ExpandEnvironmentStrings("The value of the test variable is: '%TestVar%'")