If you've placed a buy or sell order outside of market hours and later decide you want to cancel it, you can do so as long as the order hasn’t been executed yet.
Go to the Investments tab in the app.
Scroll down and tap on the stock related to your pending order.
Tap on the Activity tab to view all recent and pending actions.
Find and select the pending buy or sell order you'd like to cancel.
Tap Cancel investment at the bottom of the screen.
Once cancelled, the order will no longer be sent to the market, and no shares will be bought or sold.
Additional Notes
You can only cancel orders that are still pending. If the market is open and the order has already been executed, it cannot be reversed.
If you're unsure whether the market is currently open, you can check the order’s status under the Activity tab.