If you have a lot of Troops in your Army Camp and that you don't need and wish to remove, please follow these steps:
Go inside your Barracks and tap on the "Info" button of the Troop that you wish to remove.
On the info card, tap on the "Trash Bin" button.
Choose the number of Troops you want to remove, and then tap on 'Dismiss'.
The Troops will then be permanently deleted from your game.