What does "never mind" mean?

Don't worry about something, don't trouble yourself, it doesn't matter. For example, Never mind what I said, it wasn't important, or Never mind, you can always take the driver's test again. This expression employs mind in the sense of “care about something,” a usage dating from the late 1700s.

Also, never you mind. Don't concern yourself with that, it's none of your business, as in Never you mind where I plan to buy the new TV. [Early 1800s]