In order to close registration for an event in advance, you can either change the capacity of the Event to its current number of participants or manually turn off the booking functions of your Event.
You can also choose to pick a date and/or time that the sign-up for your event will close. The default for this option is that your event sign-ups will end on the day and at the exact time that your event occurs, but you can also choose from a list of options. You will only be able to choose an event closure time for your custom “Self-Book” templates. To pick a specified time that sign-ups for your event will end, follow the steps in the image below: