If you've finished with a board for now but think you might want to take a peek again one day, archive your board. If you're sure you never want to see a board again, you can delete it.
Archive a board
When you archive a board, you can find it in your profile in the Archived boards section, below your secret boards. It won't appear in your public profile and you won't be able to save Pins to it. You can unarchive a board at any time.