include a tick box (or similar) where you can choose a date to remove an event if 0 bookings have been made, example below.
Event Date: 05/05/22 - with 2 weeks until event start and 0 bookings cut ... Read more...
Using Zapier to sync Registration Form and Google Spreadsheet, it will be easier if the current default 00 was changeable. Then it could be fully automated. Right now need to remove manually the 00.
Sending emails to attendees should be possible to be planned for a Date - before and after an event - that means to save many email tasks to be performed automatically on the diferent dates.