How do you swipe upward previously used apps

With your finger, swipe the white bar halfway up the page and hold for a second.

This will reveal all the apps you've recently used, which is what you saw.

With your finger slide the apps upwards to force close them.

That's is all you have to do.

Hi, thats called Force Closing an App and it doesn't really preserve the battery. You normally force close an app if the app that you are using causes an issue. Here is how it is done, click on this clink How to force an app to close on your iPhone, iPad, or iPod touch - Apple Support

Hope you get really good at closing those apps.

Axel F.

How to force-quit an app:

How to force an app to close on your iPhone, iPad, or iPod touch - Apple Support

Forcing apps closed doesn’t save battery.

Here’s some reading on this topic, including info from Apple VP Craig Federighi:

https://daringfireball.net/2017/07/you_should_not_force_quit_apps

You're welcome. You honestly don't need to force close apps as iOS suspends them when you're not actively using them. It can make it easier to resume an app where you left off by not doing so, but there's nothing wrong with closing them fully if it makes you feel better.