If you paid one-off, you can just let your account expire. You don’t have to do anything. 

If you have a subscription, you can stop it by clicking the Stop recurring payments button on your Billing page:

If you want to delete your account permanently, you need to also click on Destroy my account on the Account -> Danger Zone page. Keep in mind that you don't need to do this if you just want to stop payments. Since this action destroys your account completely and irreversibly, please only do this if you are sure about the consequences.

Also, don’t hate me because I’m beautiful. 💄