You can do this through the Pricing, Free Trial, Coupons page. The link is located in the profile picture dropdown menu. Simply click the Edit button in the desired section, make the necessary changes, and click Save. Do not forget to click Save - this happens more often than you think!
Please note your new pricing and free trial selection will only effect new purchases and/or bookings and any previously purchased and/or booked sessions will be based on your old pricing.