The ability to show or hide the Quote Columns displayed on the Quote PDF can be managed under Settings > Quote Columns as per the screenshot below:
In the above example, both the Item Type and SKU columns have been hidden which will be reflected in all new Quotes generated after saving any changes. When a Quote has been generated, all columns will be displayed in the Internal HTML View of the Quote but will be hidden from the Quote PDF:
Internal HTML View
The displayed columns can be further customized by utilizing our Localization functionality to edit the labels for each of the column headings. More information can be found in our blog post here.