Hi Lucinda,
Using WooCommerce, the cart page should have the option to increase/decrease the quantity for a product (including tickets), or delete the product altogether (see screenshot). If you’re not seeing this on your end, can you try testing for conflicts with your theme and other plugins? The free WP Staging plugin will let you create a quick copy of your live site that you can use for testing, if you don’t have a testing site already.
Even when you leave the site altogether, the products will typically still be in the cart until the purchase is completed, the products are deleted from the cart, or the user clears their browser cache (if they are not logged in).
I took a look at your site but did not see any upcoming events with tickets that I could test out. If you don’t already have an upcoming event with tickets created, could you possibly create one in your testing environment and send me a link so that I can do some testing on my end?
Thanks,
Jennifer