1. Click your desired folder in the Workspace pane.
2. Click 
on the toolbar;
Or, go to File --> Delete... from the top menu.
3. Click Yes to confirm your deletion in the Delete Item(s) form.
Files opened in the Content pane are closed after the folder containing them has been removed.
Note
You cannot remove:
Workspace root folder.
Multiple items from different hierarchical levels at the same time.
The Delete Item(s) function is disabled in case of selecting the root item and/or multiple items on different levels in the Workspace pane.