Deleting a point is most often done with an irregular TIN than it is with a grid but it can be done to both. To delete a point, simply get as close to the point with the mouse cursor as possible and right click to bring up the context menu and delete the point. Deleting points from gridded data marks the data as deleted or missing but does not actually delete the point location from the dataset. To do so would make the data into an irregular TIN. This is unnecessary.
