TurboTax actually does not support grouping rental activities for real estate professionals so there is no screen for doing so
While it's true that H&B does not ask any questions or provide any screens or selections concerning aggregation, you can do so manually with Home & Business if you know how. So is 2019 the first tax year you have aggregated your rental properties?
If so, the only way to undo it correctly is to completely and totally delete all rentals and start over from scratch. If 2019 was your first year of doing this, then you didn't import anything from a 2018 SCH E.
If you had rentals on the 2018 return that were not aggregated, then the only possible way to import those rentals correctly into TTX 2019, is to close the program, delete the .tax2019 file in the documents/turbotax directory and then start your 2019 tax return over from scratch.
