If you did not aggregate the properties on your 2018 return, then the easiest and simplest was to do this to ensure you don't make mistakes by trying to undo this manually, is to clear your return and start over from scratch. That way, you can import all the data from your 2018 tax file again.
If using the online version, you'll find the option to "clear and start over" somewhere in TOOLS on the left. Do note however, that if you have already registered or paid your online TurboTax fees, this option is not available and is not possible.
If using the CD version of the program, close the program and then delete the .tax2019 file located in the documents\turbotax directory. Then fire up the program again and it's "as if" you just installed the program and are opening it for the first time ever.
