Hi @Michal_Linden, welcome to the Asana Community Forum!
If you are the plans Billing Owner, you can cancel your free trial following the steps in this article: How to Upgrade & Manage Billing Options in Asana | Product guide • Asana Product Guide. If you have any issues to cancel, I recommend you to contact our support team so we can investigate further: How to contact our Support Team ✉
I hope this helps! 