Time needed: 1 minute.
The iPhone XR does not have a Touch ID fingerprint scanner, meaning there’s no home button to press to get to the App Switcher screen to close apps. You’ve to swipe up from the bottom of the screen to get to the App Switcher on iPhone XR, and then swipe away the apps you want to close.
Open App Switcher by swiping up bottom of the screen
Swipe up from the bottom to the middle of your phone’s screen to bring up the app switcher.
Get to the app you want to close
Swipe left or right to get the app you want to close.
Swipe up on the app to close it
Swipe up on the app you want to close from the App Switcher. It’ll be gone.