Eliminating the sorting icons from column rows

I have tried searching for this in various ways and haven't found anything relevant so I am posting this as a question and hopefully someone can help out.

I have sorting enabled using "bSortable" in "aoColumnDefs" and defined like so:

"aoColumnDefs": [
{ "bSortable": false, "aTargets": [0] },                      
{ "bSortable": true, "sWidth": '100px', "aTargets": [1] },
{ "bSortable": true, "sWidth": '110px', "aTargets": [2] },
{ "bSortable": true, "sWidth": '100px', "aTargets": [3] },
{ "bSortable": false, "aTargets": [4] },                      
{ "bSortable": true, "sWidth": '100px', "aTargets": [5] },
{ "bSortable": true, "sWidth": '100px', "aTargets": [6] },
{ "bSortable": true, "sWidth": '200px', "aTargets": [7] },
{ "bSortable": true, "sWidth": '100px', "aTargets": [8] }
 ],

The "bSortable" option causes all the rows that have sorting enabled to display the sorting icon on each row. I just want the sorting icon to appear in the header for the columns that need to be sorted. I am not sure if there is something I am doing wrong in the I am defining it above or should I target this in CSS and somehow force it not to display the icons in the rows.

Thank You.