IOCTL_KS_DISABLE_EVENT control code
An application can use IOCTL_KS_DISABLE_EVENT to rescind a previous request notification. The application specifies IOCTL_KS_DISABLE_EVENT in the IoControl parameter of a call to KsSynchronousDeviceControl.
The application places a pointer to a structure of type KSEVENTDATA in the InBuffer parameter. This is the location of the original KSEVENTDATA structure that the application instantiated at the enabling of the event. To disable all active events, a client specifies a NULL pointer and length of zero in the InBuffer and InLength parameters.
If the request is successful, the Status member is set to STATUS_SUCCESS.