I made a video showing how you can defeature a part with ViaCAD 2D3D 9. The key tool is the Remove Face command which can be used on collections of faces such as blend, chamfers, holes and cutouts. The "tip" in this video shows a recent code change that combines the Deep Select tool with the Delete key to provide a quick method to remove faces.
Normally defeaturing is associated with removing extra detail for CAE prior to meshing. But I find this tool also good for completely removing a feature and replacing with a new or modified feature. Some examples include removing a radial blend and replacing with a chamfer or replacing a countersunk with a counterbore.