When viewing the Project Sketchbook through the View Sketchbook button, you can only delete one item at a time. To delete multiple items at a time, you must view your Sketchbook items through the Library box.
• Use CTRL+click to select multiple files at once.
• Use SHIFT+click to select a range of files.
• Use CTRL+A to select all the files in that folder.
You must be viewing the library of the item you want to delete. The Sketchbook items shown in the library are specific to that library. For example, if you want to delete fabrics, you must go to the Fabric Library.