How do I remove a sign panel in OpenRoads SignCAD?

Answer:

1) From the Preferences menu in OpenRoads SignCAD, pick "Allow Panel Selection" and use the Select tool to window select the entire sign (shortcut - hold the <ctrl> key and use the Select tool to window select the sign). NOTE: Signs created using the Standard Sign Panel will show the panel selection box in the middle of the panel.  Signs created using the Rectangular Panel will show the selection boxes on each of the panel corners as shown below.

2) Press the <delete> key on the keyboard to remove the selected sign from the workspace.

3) Save the file (File>Save).