Close other apps running in the background

Android

Close all apps: Swipe up from the bottom, hold, then let go. Swipe from left to right. On the left, tap Clear All. 

Close all apps on Android Go: Swipe up from the bottom, hold, and let go. At the bottom, tap Clear All.

iOS

Step 1: From the Home Screen, swipe up from the bottom of the screen and pause in the middle of the screen. If you’re using iPhone SE, iPhone 8, or earlier, double-tap the “Home” button to show your most recently used apps instead.

Step 2: Swipe right or left to find the app you want to close.  

Step 3: Swipe up on the app's preview to close the app.