First of all do you mean to get ready for NEXT year 2019 program? Or are you asking about a current 2018 return you are doing now in 2019?
Actually it doesn't matter. Each year is totally separate. If you don't want an incorrect return transferring into the next year then just don't transfer from it. Start a brand new return. Your return is kept in the .tax2018 file and not stored in the program. So you can even delete the wrong .taxyyyy file.
