code: @SuppressWarnings("unchecked")
    public final E remove()
    {
      Thread thread = Thread.currentThread();
      ClassLoader loader = thread.getContextClassLoader();
  
      for (; loader != null; loader = loader.getParent()) {
        if (loader instanceof EnvironmentClassLoader) {
          EnvironmentClassLoader envLoader = (EnvironmentClassLoader) loader;
  
          return (E) envLoader.removeAttribute(_varName);
        }
      }
  
      return setGlobal(null);
    }
docs: Removes this variable
  
  @return the old value