How do I analyse data for DoE study with a categorical factorial?

[#1]

In DoE study with a 3-level categorical factorial, can you exclude and hide data for one category and analyze the data for other categories?

[#2]

You can use a Local Data filter on the Results Display and select the factors you want to keep in the analysis.

I will not comment on the wisdom of doing such 

[#3]

Why do you want to exclude data?