To close a sprint just click on the button in the top right corner of your agile board backlog.
If your team hasn’t finished all items, you can now decide what to do with each. By default, they will be moved to the next sprint, but you can also close them or move them to the backlog.
If your team has finished all items, you can just confirm it. Congratulations, your team has successfully completed a sprint!
Now you’re ready to start a new sprint.