how i can destroy "Summoned Cards"

[KorvusXVII]

how you know, have cards that are useless, i'm wrong because i have activated some of these cards already, and my question is: how i can do to destroy or remove it?, i wanna these slots free to better cards, but i don't know how destroy it and free the slot, any1 can help me with it? would thank you for the help
next, the image that show my problem:

(como sabran. hay cartas que son inutiles, me he equivocado pues he ya he activado algunas de esas cartas, y mi pregunta es: ¿como puedo hacer para destruir o remover tales cartas?, quisiera tener esos espacios libres para cartas mejores, pero no se como destruir la carta y liberar el espacio para una mejor, alguien podria ayudarme con esto? le agradeceria la ayuda
la imagen que muestra mi problema: )

[R2sucksbad]

lol, you cant exchange them, nor do you want to destroy them.

you use the duplicate cards to increase the level of the cards you already have activated.

[nightsuwayne]

it was cool

[noob9841]

there are no cards to replace them with, there are just the 4 and maybe an orange one in the middle later, but i have never heard that the orange ones exist

[Sufference]

you don't replace them.. you level what's already there... try going into card page and clicking on "1 click upgrade" - they will magically disappear