Hey ​@MINDLAB60512! Thanks for reaching out here! I added steps below on how to cancel your plan. Let me know if you have any questions.
 

From your Calendly home page:

1. Navigate to the Admin Center and select Billing.
2. On your Billing page, select Change plan, then Upgrade/Downgrade.
   
3. Choose the plan that best suits your scheduling needs. 
   • You can cancel your subscription by switching to Calendly's free plan.

     If you want to delete your account and remove all data from Calendly, see the instructions here.

If you’d like to discuss payments on your account, you can reach out to our billing team at billing@calendly.com

As described, it doesn’t work and it’s a lack
I decided to cancel the subscription directly from Paypal : efficient and reliable

Where’s is the free plan ?

Hi there - After clicking Downgrade Plan on your billing page, you should see a button below these that says ‘Upgrade to the free plan’:

Let me know if this appears