I started with the LingQ Mini Stories: Story 1 in the Chinese course, and clicked on the capital A present in the text and now when I do my reviews I am presented with a card that just has the letter A on it. Is there a way to remove it?
Have you tried to select it in a story again and click the “ignore” button, or “x” on the keyboard? That ought to change its status to ignored, removing it from the list of words you’re actively learning.