If you want to have a shareable URL to show your designs you can do it from the VIEW mode: launch it using the PLAY button at the top right of the file, and you’ll find a SHARE URL button to create the link at the top right. Copy and send that link for other people to access the design.
To destroy a link press the button “Destroy link” and confirm the action. The link will cease to exist and will be no longer available, so be careful if you’ve already shared it… More information: