The application must cancel any outstanding timers by calling the timeKillEvent function before it frees the memory that contains the callback function. To cancel a timer event, it might call the following function.
void DestroyTimer(NPSEQ npSeq)
{
if(npSeq->wTimerID) { // is timer event pending?
timeKillEvent(npSeq->wTimerID); // cancel the event
npSeq->wTimerID = 0;
}
}