To Undo any actions, type Ctrl-Z or click the 'Undo' button in the ribbon toolbar.
To Redo any actions, type Ctrl-Y or click the 'Redo' button in the ribbon toolbar.
Streetscape Pro will remember up to about a hundred actions. Please note that when dragging the slider control to change the Orientation of the street, this may 'use up' several actions very quickly.