Create a TIN surface from those x,y,z points
Export to DEM per whatever grid parameters you want.
Throw away the TIN surface.
Create a new grid surface from the DEM.
have you searched in the help or just asked?
Searching is faster then waiting for an answer (even with this quite fast forum).
Looking to the Civil3D-help by <F1> (or >>>this link<<<), that might happen:
(I used exactly the wording of the thread)
- alfred -