Ragic has a forever free version that you can use, but for any reason, you can still delete your Ragic account.
Please make sure that you have exported all your data beforehand, or you do not have any data of importance on your account.
Please click the hamburger icon on the upper-left of the database and navigate to the DB Maintenance Menu page. You'll see the Delete My Account option on the bottom.
Please check this documentation if you are looking to cancel payment to your account.