In order to cancel your account all you need to do is head to 'Settings' then "Plans & billings". Once you're inside the billing page simply click on "Cancel account" in the bottom left corner.
You will still have access to your current subscription until the last day of your current billing cycle, so you can still publish ads and take part of the features you have paid for. Once the current billing cycle ends you'll be downgraded and your account will be dormant.
If you want to be sure that your templates are saved, you should keep your subscription running. Qwaya reserves the right to remove your data once your subscription is inactive.
You can read more about canceling your subscription here.