"I've tried every imaginable check box, but no joy! Any ideas about how to get rid?"
Hi @Phil2595662544fy ,
I suppose that story is tagged with an XML tag and your view is showing the tag according its color.
If you show the Structure pane and the Tags panel you could see what's going on:
View > Structure > Show Tagged Frames
View > Structure > Show Structure
Window > Utilities > Tags
I'd be careful of getting rid of the tags.
Perhaps they are needed downstream in the workflow by another user.
( Adobe Community Professional )