How to view any hidden data (Strikethrough data on the document) in a word document

Hi

We had one of the staff received a word document and he filled in some details on the document.

When he click to print the document – on the preview it shows some extra data.
Not sure how this extra data is hidden (It is highlighted in different color and Strikethrough)

Is it possible to see this data when I am normally working on the word document so that any unwanted data is removed.?

Do I need to enable any settings on the word document to view any Strikethrough data on the document?
Any help much appreciated. 
 
Thanks in advance