I want to turn off auto extension because I don't plan on renewing my license. However, I can find no way to do so in the app, and I can't find anything online where I can log in to manage my subscription. This type of tactic makes my blood boil and I will definitely want to cancel now, whereas I was on the fence before.
There was a 'Manage Subscription' button in Options>Licence key, but for some reason that went missing a couple of months ago.
https://support.ccleaner.com/s/article/how-do-i-manage-my-ccleaner-subscription?language=en_US
The other way to do it is to contact support and tell then that you want to cancel your subscription:
There is a form here: <a href="https://support.ccleaner.com/s/contact-form?language=en_US&form=general" ipsnoembed="true" rel="external nofollow">https://support.ccleaner.com/s/contact-form?language=en_US&form=general</a>
Or you can send an email to support@ccleaner.com
However be aware that there appears to be problems with support at the moment, with reports that users are not getting replies to their emails.
There is of course always the option of telling your bank/card/PayPal not to make any future payments for the subscription.