Here are the steps you need to follow to archive your board:
Step 1. On your Dashboard page choose the board you want to archive by clicking on the 3 dots icon (ellipsis)
Step 2. Choose the option “Archive”
Final Step. Now click on the button “Yes, archive it!” to archive your board.
Note: After a board is archived, only the board's creator will be able to access the board and it won't be accessible by anyone with the URL anymore. Also, the board will always stay archived unless you delete it.
Here are the steps you need to follow to unarchive your board:
Step 1. First, you need to access the archived board page by clicking on “Show archived/deleted” choose the option “Yes”.
Step 2. Go to the board you want to unarchive and click on “Unarchive”
Final Step. Now click on the button “Yes, unarchive it!” to unarchive your board.
Note: Once you unarchive a board, people with the URL will be able to access it again.