The Sheet Set Manager automates and enhances the process for adding views to a sheet.
When you place a sheet view on a sheet, all the layers in the current drawing (including layer 0) are frozen in the new viewport created by the view. The layers are shown as frozen in the VP Freeze column of the Layer Properties Manager.
If you need to remove a sheet view from a sheet, you can delete the layout viewport to remove the view. However, to remove all unused items, you need to detach the xref and delete the named paper space view.