To delete a node with the keyboard:
(1) First make sure the tree has focus, otherwise the tree won't receive your keyboard commands.
You can always click on the tree to give it focus.
(2) If the tree-node that you want to delete is not selected, use the Up/Down Arrow keys on your keyboard to select a node.
(3) Press the Delete key on your keyboard
(4) A dialog box appears, asking you if you want to delete the node. Click Yes.