To remove a field from a card, you'll need to remove it from the card category, go to settingsgo to card categories and then select the category of that card e.g. Talent.

From here you can edit the settings of that card category including removing a field from that card. 

Go to "Linked Fields" to select the field you wish to unlink, press the bin icon to remove.

Hit "Save" in the bottom right corner when you are finished to save the changes you have made to your category.