In a plan, elevation, or section view, select a crop region and click Edit Modify | <view type> tab Mode panel Edit Crop.
Use the tools on the Modify and Draw panels to edit the crop region as needed. Modify the existing lines or delete the lines and sketch a completely different shape.
When you are finished, click Finish Edit Mode.
Note: If you want to reset an edited crop to a rectangular shape, select it, and click Edit Modify | <view type> tab Mode panel Reset Crop.