The Rotate Labels command is used to rotate labels on distribution equipment, feeders, and equipment connections on the one-line diagram.
To rotate a label, go to
Ribbon: DM Electrical->One-Line Diagram-> 
Rotate Labels
Pulldown Menu: DM Electrical->One-Line Diagram->Rotate Labels
You will be prompted to select the label to rotate.
Select label to rotate:
You can then specify a rotation angle for the selected label.