Yes, as long as you didn't mail in your return, you still can change the filing method.
- Log in to your account.
- Go to the section "Your Tax Returns & Documents." and click Show.
- Under 2019, look for a link "Add a State" and click. (that doesn't really add one; that's just to open the return back up.)
- Once the return is open, select File from the left menu.
- In step 3, change the filling method to e-file your return.