At the beginning of the process TT asks what's changed since the last tax return. I inadvertently selected "I bought a home". I did, but not in 2018. How do I remove?

Those questions are not recorded in your tax return.  So, TurboTax will ask you about your home when you get to the deductions section.  When TurboTax asks if you received a 1098 for your mortgage, just answer NO, and you will skip that entire section.  

If you accidentally started to enter home mortgage interest, type 1098 into the search bar, hit enter and then use the Jump to 1098 link to be taken to the ''Here's your 1098 info''.   Then click on the trash can icon next to the 1098 to remove it, see attached.