This guide will help you to force any app on your Apple Watch when it stops responding or in the case of you want to stop all apps from running in the background. You can apply this useful method to close apps on your Watch instead of rebooting the entire Apple Watch.
When you are in the application that you want to close, you need to press & hold the “Side” button.
By pressing & holding that button, your Watch’s screen will turn off. Next, let press & hold the “Side” button again, it will return you to the app, quit the app and redirect you to the home screen. The application you want to close is now closed.
However, if the app you have selected to quit is showing up in the Glances, you are unable to stop it because it still running after you force it to close. The only method to close an application in Glances of your Apple Watch is to remove the app from the Glances.
By any reason, if you can’t force a particular app to close with the above method, you can always restart your Watch. To reboot your Apple Watch, you need to press & hold the “Side” button until the slider with “Power Off” text shows up.
Just slide the slider, wait for several seconds to your Watch turn off, and then press & hold the “Side” button again until you see an Apple logo, to power it on.