Step 1. On your Dashboard page choose the team board you want to move by clicking on the 3 dots icon (ellipsis)
Step 2. Choose the option “Move to public”
Final Step. You’re going to see a message that says:
“Moving this board to the public will make it accessible by anyone with the URL, are you sure about it?”
Now click on the button “Yes, move it!” to move your team board to a public board.
Note: It´s important to remember that only the owner of the team is able to move a team board to a public board.