If you're done with a board for now but think you might want to sneak a peek again someday, 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 on your profile in the Archived boards section, below your secret boards. It won't show up in your public profile and you won't be able to save Pins to it. You can unarchive a board at any time.