It's not possible to completely delete a ticket from your RSVP tab. We recommend refunding and revoking that ticket so it will free up the ticket quantity.
Even if the ticket is $0, the process is the same. This helps you keep a true record of all your sales, especially when dealing with money or if you have other team members working on the site.
If you'd like, you can also duplicate your current page and start anew keeping the same domain! Check out how to accomplish this here: