Removing Incorrect Sales Tax from Appointment + Charges

Our California customers are getting charged sales tax on the service they are signing up for, which is incorrect! How do we remove this erroneous sales tax?

Our Website is here: http://pilateswithteresa.com/
We are using Appointments+ here: http://pilateswithteresa.com/make-an-appointment-2/

I have given you access to the site via WPMU DEV Dashboard.