Shortcut to quickly kill an app I have Android 4.4.2, it's rooted.

There are some apps that I execute and don't shutdown and I have to kill them. I use GO TaskManager EX widget to get rid of them, but that requires me open its dialog, look for the app icon and click it to have it killed.

Is there an app or some command I can add to a shortcut, so that I just click its icon and that app is killed in case it's opened?
I have always felt the need for this and been using in KitKat and Marshmallow. 

Since your device is rooted, it's easy. Install Gravity Box Xposed module and under Navigation bar tweaks &rarr; Custom key settings &rarr; Long press action (Kill foreground app)  and choose your Icon Style/Set custom image for the icon to sit always on your Navigation Bar. Simply press it to get rid of the unresponsive app

You see the icon on extreme left, below Yahoo mail