Profile → Billing → Cancel. It takes effect at the end of the current period, and you can export everything before it does.
Go to Profile → Billing → Cancel subscription. No email, no phone call, no retention flow.
Cancellation takes effect at the end of the period you've already paid for — you keep full access until then.
Before you go, run a full export. It downloads every receipt file plus a CSV of the metadata. That archive is yours permanently and is exactly what you'd need if the IRS ever asked, whether or not you have an account here.
If something specific isn't working for you, we'd genuinely rather fix it than lose you — reply to any account email and tell us what broke.