Handling the British National Corpus 

If you don't want to see the tags, choose View | Tag Hiding in the menu

 

and in that, choose the kind of tags you do or don't want to see.

 

The tag file tags are those which you have defined, any others are "undefined". The Sentences, Paragraphs, Headings and Sections tags are those defined in the main WordSmith help here.

 

Alternatively in the main toolbar (switch it on in the View menu) you will see a button to do the same job.