I see the ability to add columns and filters to views on Transaction sublists. But can you remove unnecessary columns? Transaction sublists where you perform bulk operations such as Pay Bills, Approve Sales Orders, Invoice SO’s etc.

If you mean to remove columns from a "View", then you would remove the "results" selections from that view to remove those columns. If on the other hand you mean to remove columns from a transaction's sublist, you would do that from the "Customize Form" (or navigate to Customization > Forms > Transaction Forms, and choose the forms that you want to update. Choose the "Sublist Fields" tab of the form's settings to show or hide available columns.