we ask the developers themselves to close the sprint once they completed the sprint. Just want to confirm, if it has to be closed by TL after he reviewed the tasks completion.
The Product Owner should be responsible for closing a verified sprint after a successful demo has been done. The PO should check whether the stories have been "done" to completion in that they meet the correct acceptance criteria.
The developers can "close" the sprint, but the PO needs to verify the completeness of them and "officially" close the sprint and call it done.