If you drag down the notification bar on LG G4, you'll notice a bunch of quick system settings as well as the option to adjust the brightness and volume. If these volume control and brightness settings are taking too much space, do as follows to remove volume control from notification panel on LG G4 as well as the brightness adjustment control:
1. Drag down the notification bar
2. Now swipe the system toggle buttons to the left and touch the Edit button
3. There you should see the Brightness and Volume options.
4. Mark/unmark them to hide/show the brightness and volume controls in the notification panel