private Account myAccount;
Order stopOrder = null;

 
protected override void OnStateChange()
{
  if (State == State.SetDefaults)
  {
      // Initialize myAccount
  }

}

private void OnExecutionUpdate(object sender, ExecutionEventArgs e)
{
  // Cancel the stop order if an execution results in a long position
  if(e.MarketPosition == MarketPosition.Long)
      myAccount.Cancel(new[] { stopOrder });
}