I worked with a customer who has exactly posted the query like this:
‘In the company admin c360 layouts for the person field and the field/values shown. I'm trying to remove the "Comments" one from the "DETAIL VIEW". I can select "Comments" and delete it and save the change but when I go back in, "Comments" is added back at the top.’
Further investigation showed that standard and system fields cannot be removed. Customer wanted to know why does it allow removing field without a prompt that because of this (system or standard) field type this cannot be removed.