Deleting cards in Kanban board on the web requires to click on “…” sign and selecting delete which is time-consuming and frustrating if you are deleting multiple cards (which happens a lot especially for developing workflows)
Just like dragging a card to another column, when user start to drag a card, an area for trashing cards will appear on UI, so if user drags the card into that area it will be removed quickly. Offering a short “Undo” time afterwards, of course.!
Visual design draft: