How to close open apps in Apple watch(os3)

Hi

It is neither necessary nor appropriate to close apps on Apple Watch in order to preserve battery life.

Apps that you have chosen to add to the Dock may update their content automatically, depending on their features. If preferred, you can remove apps from the Dock:

Switch between apps using the Dock on your Apple Watch - Apple Support

Apple's tips for maximising battery life on Apple Watch are available here:

https://www.apple.com/batteries/maximizing-performance/#watch

If any given app is not working properly, it may instead help, in the first instance, to restart both your iPhone and Apple Watch (normally) before following any further troubleshooting steps:

Restart your Apple Watch - Apple Support

One thing to try -

Did you try closing them on the phone by double tapping the home button and then swiping to close the iPhone connected app?

thanks Vipin2007