Is the workbook you attached a simplified version of your actual situation because in the example you show there is no need to add a combined column, just remove that column and right-click on Category, select Sort and choose to sort Descending on Sales and SUM:
Or are you asking how to not show hidden fields, regardless of what they're used for?
If you are asking about not showing hidden fields when exporting then there are a few threads about this topic.
The final answer in the link above might help, mentioning methods of exporting
This has a wider discussion including some tableau ideas that could be voted up.
You will get option to select the columns which you want to export in excel when you are attempting export from tableau server.
I tried doing it from the Tableau desktop but it is exporting everything.
That is my Problem also.
while exporting to the excel all hidden columns are coming in the export file.
It is not abut the sorting . My Problem is to control the Hidden columns while exporting to excel.
i don't want to see the Hidden columns in the excel file.