Here's how to sell a stock:
Click on 'US Stocks' on the app homepage then click on the particular stock you wish to sell under the 'My Stocks' section.
Tap the 'Sell' button to complete the sale.
Select your preferred sell option.
Input your sell details.
Tap Review Order.
Tap Sell.
The money from the sale will be available in your Buying Power immediately after the sale is executed to enable you to reinvest it. Please be careful of good faith violations!
Read about that by clicking here.
If you wish to withdraw the money instead, it will settle and be available for withdrawal within 1 business day. Once it is available, you can withdraw it by following the steps here.