If you want to exit the trading account, there is a three-column icon on the upper right. Click it and several functions will come out. The third is "account cancellation". Just click on it.

It's easy if you quit the software. Just like other IPHONE software is turned off, press the only key at the bottom of the phone screen twice, and the running software will be displayed at the bottom of the phone screen. Just click on one and hold it for a while, and a cross will appear at the top right of the icon. If you want to turn it off, click the cross. You know, it's a little dizzy.