Locking a board is a feature that prevents any edits or additional posts for a board. This setting is only available to the board creator or an org admin if on business/enterprise plan. See the instructions below for more information how to lock/unlock a Kudoboard:
1. When viewing the board select the Settings option below the board title.
2. A settings menu will appear with a Lock Board toggle option. Clicking the toggle will move it to the right to lock it and the left to unlock it.
As the board creator / admin you are able to lock or unlock a board at any time.
See the below How To Video for more assistance.