Alexa was a free platform back then in 2015 but a recent update which made new user to first of all get one of it premium package and this made the platform a little bit hard for newbies .
Below are some simple steps on how to cancel subscription plan on Alexa.com just follow it step by step..
Go to your Account Management page.
Login with the same account you used to sign up for the subscription.
Select ‘Manage Subscription‘ under the plan you would like to cancel the subscription for.
Select ‘Cancel Subscription.
Read the prompt on screen, if you would still like to cancel select ‘Cancel Subscription.
Now remember that if you skip step 5 your subscription will not be canceled.