Deleting elements from a soild polysurface

I can’t delete points on a particular object.

If it matters, it’s an imported sketchup object, but it isn’t part of the usual chaos of nested components. It’s just an individual closed solid polysurfacse.

I’m trying to remove faces.

Images, Files, Expected Results?

THanks. Sorry.
This object is a solid polysurface forming a long square sectioned hull-type tubel. I want to delete all faces but the outside and cap the ends so that it’s a long box instead of a long tube.
IN the below image I’ve secleted all the points forming an inside vertex. When I hit delte, nothing happens. It’s not on a locked layer. It’s not a great object because it’s not nurbs but facetted faces. (It’s an import from sketchup.)

Hello - ExtractSrf the top and bottom faces, delete these and the inner part then Cap the remaining part.


Thanks Pascal. Can you tell me why it’s resistant to simply deleting points? I don’t recall an object being resistant to that.

Hello -SolidPts are never ‘deleteable’ Curve control points are (minimum two) and EditPts are, mesh points are deleteable and surface points are, by rows only, down to a minimum of four - two in each direction.