If you have a lot of excess Spells crafted and wish to remove some of them, please follow these steps:
Go inside your Spell Forge and tap on the "Info" button of the Spell that you wish to remove.
On the info card, tap on the "Trash Bin" button.
Choose the number of Spells you want to remove, and then tap on 'Dismiss'.
The Spells will then be permanently deleted from your game.