Long-press on one of the bottom icons on the Home screen will show the trashcan on the bottom right side. Drag icon to that to remove it.
To add a new icon, I found that you have to add it to one of the screens, first. So, select a screen, press the APPS icon on the bottom right, drag the icon you want to the upper part of the screen.
Then, long-press that icon and you can drag it to the very bottom of the home screen.