If you have added too many icons of the app on Home screen of your Android 6.0.x Marshmallow smartphone or device, one day you will feel the need to vacate some space for the further icons of apps.
Cleaning the Home screen is a typical matter which is so simple in nature that you may do so, easily. But, you are not understanding the process, see the instructions.
Instructions
1. Select the icon of app which you want to remove from the Home screen of your Android 6.0.x Marshmallow device and tap it for a while. It will become unstable and is ready to move it.
2. In addition to it, see; at the top of the screen but below the status bar, 2 buttons will appear; ‘Remove’ and ‘Uninstall’.
3. If you are willing to remove the icon of the app, drag this app with your finger upon the button, ‘Remove’. The color of the icon will change to red or any other color – depending upon your device – and the icon will be removed from the Home screen of your device.
4. And see the icon of app has been removed from the Home screen. 
Similarly, you may remove many unwanted or unnecessary icons of apps from the Home screen of your device.
That’s all!