Hi @Federico_Barusco, sorry for the trouble. When you click “Select a plan”, there should be an option “Not ready? Go back to a free Basic plan.”. Can you please test if that works? If not, please share a screenshot of what you see.
That said, I see that you already have an ongoing case with Support, and if you still don’t see the option to select the free plan, I’d recommend following up in your email thread, and our Support team will be able to disable the trial for you. I hope this helps! 