Log in to your account (either on the app or website).
Scroll down and look for a section called "Manage your extras" - there should be a big + underneath the Disney symbol.
Click this and there should be an option either to not auto-renew or manage this extra.
From here untick the option to auto-renew and once your free period runs out your account will be closed.
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here