There is no way to delete documents directly from the task pane, but you can
delete them from the MRU list at the bottom of the File menu, and this will
remove them from the task pane as well. To do this, press Ctrl+Alt+Hyphen.
The mouse pointer will change to a big minus sign. Hover the mouse over the
File item until the File menu opens, then click on the document you want to
remove. Use this shortcut with care, as it will delete *any* menu item you
click on.