Good Evening,
For Turbo Tax Online products you can skip 2018 and when 2019 becomes available you can just sign into your online account. However please remember that if you do not use Turbo Tax for 2018 then you will not be able to import information into you 2019 return.
If you are currently a participant of the Turbo Tax Advantage program you would have to cancel the subscription. Please be advised that if you cancel the subscription it will not be available to you in the future. Turbo Tax is currently grandfathering out that program and no longer offers it.
Sharon C.-Turbo Tax Specialist