How to cancel subscription?

If you can't login and do it yourself, call the helpdesk and ask them to cancel it for you.

Are you on the DESKTOP  program Advantage auto renew plan?

You can sign into your Turbo Tax Advantage account and under Your Product, select to Remove Product.  Once you remove the recurring product order, the Turbo Tax Advantage subscription will be cancelled as well.

How to cancel Turbo Tax Advantage

https://ttlc.intuit.com/community/downgrading/help/how-do-i-cancel-my-turbotax-advantage-subscription/00/25548