Estate or trust id for non-existent K-1

Use the "Delete a Form" tool to remove the Schedule K-1 (and any associated worksheets).

See: How do I delete forms in TurboTax Online?

After deleting the Schedule K-1, log out of the program. When you log back in, use the Delete a Form tool to confirm the Schedule K-1 has been removed from the list of forms in your return. 

Why does this happen? Once you enter (or import or transfer) certain information, the program creates or updates forms and worksheets that use that information. In many cases, you cannot "change" that information in the interview process - in a manner of speaking, it has been "written in ink" on the forms. You have to delete the form and any associated worksheets in order to correct.