About Editing Surfaces
There are several ways that you can edit surfaces:
Redefine the boundary or internal curves using the Curve Edit tool, and then regenerate the surface.
Add or remove boundary or internal curves by selecting the surface, right-clicking, and choosing Edit Definition from the shortcut menu.
Add and move reparameterization curves by using the Reparamaterization mode when you edit the definition of the surface.
Edit the connections between surfaces using the Surface Connect tool.
Use the Surface Edit tool.