old iphone 6 icons visible behind iphone 12 icon

To load IOS13.2 on iPhone 6 Plus I had to delete most apps on my 16 mb phone...but afterward had ghost icons on screen with no apps behind them and no way to delete ghost icons. Upgraded yesterday to iPhone 12. Now have ghost icons and everything from 6 plus screen visible behind 12 icons. How to get rid of all old icons none of which have apps behind them. If touch or hold down old icons nothing happens so cannot use normal way to delete.