If your trading system includes a specific exit signal (as does the zero line cross trade), then you can exit your trade via either TWS or your order entry software. If your trading system does not have any exit signals, then you should wait until either your target or stop loss orders are filled, which will exit your trade accordingly.
Once one of your trade's exit orders has been filled, you should make sure that any pending orders have been cancelled via either TWS or your order entry software. If necessary, you can review your trade and your realized profit or loss via your trading software.
