To close registration, either update your registration end date or change your event capacity.

To change the registration end date or event capacity for Simple or RSVP Registration, go to your Event Dashboard > Setup > Registration and scroll down to change the registration end date and the event capacity.

To change the registration end date or event capacity for Ticketed or Multi-Event Registration, go to your Event Dashboard > Setup > Registration > Tickets and change the close date and quantity on all tickets.