How do I delete a face or poly in nifskope?

[dragonslayer2k12]

I know how to delete blocks but I only need to delete some faces or polys not the whole block, how do I do that in nifskope? I have tried selecting the face or as nifskope calls it triangle and then pressing the delete key or double click left/right mouse buttons and everything else I could think of but I still can't figure out how to delete a single triangle or several of them. I hope it can be done, it is only logical that triangles could be deleted since we can delete blocks which also deletes triangles and verts. Anyone figured this out yet can you post how to do it thanks.

[throttlekitty]

NifSkope can't do that type of editing on models, you'll need to do this in a 3d modeler, such as Blender.