You can use the Rotate tool to rotate a deck about a selected point.
To rotate a deck:
Select the deck by clicking on one of its edges. A grab handle is displayed at each corner.
Right-click and select Rotate, or select Edit > Modify Elements > Rotate.
Hover your pointer over the point you want to rotate around.
Click and drag to rotate the deck, then release your mouse button.
Note: When you rotate a deck, the direction of the deck boards does not change. You can change the decking direction if you want.