Widgets on iOS are not the same as widgets on Android. But if you drag down the notification bar on your iPhone you'll see some widgets in the notification center, including the Stocks widget. To remove stock from iPhone notification center, do as follows:
1. Drag down to notification bar to open the notification center.
2. Make sure Today tab is the active tab
3. Skip all the notifications and widgets and scroll all the way down to the Edit button
4. Tap the Edit button and the notification center customization panel opens.
5. To disable and remove stocks from the notification center on iPhone, first hit the Red minus icon next to the Stocks and then tap the Remove button
Tip: To bring back and add Stocks to the notification center on iPhone, tap the green plus icon next to the Stocks in the list of Do Not Include widgets