Note: Make sure you are logged in and in the correct event
You can always set a 'Last Registration' date for your events. After this date, people are not able to register anymore.
Go to 'edit general info' via the dropdown or via event website.
Set your registration deadline by filling in the dates.
Last registration day: last day people can start a new registration.
Last registration changes day: last day people can adjust their registration.
Once set, simply click on 'Save'. The registration will be closed at midnight, 00:00 hours on the given date.