If you want distinct records, you can put all the selected columns on the "Group By" tab--just hit the "Propose Columns" tab.
You will have to unbind any rules bound to a column you want to remove and also remove that view from any tasks before you can remove the column. An alternative solution would be to keep the column name in the view but re-map it to a static value of 0 or null or something (so it does not reference the original table) in your view.