Removing parts of a furniture or object

[JenNJen]

Hello.
How do you edit a furniture, or in my case a staircase, to split it in half or remove some bits of it?
I need the staircase to be half the height of the ones in the library.
If I resize, it looks ridiculous because there are too many steps. I need to remove 6 steps at least as it is going half a floor up.

Thanks

[Puybaret]

It's not simple: you'll have to modify the OBJ file of the 3D model with a separate program like Blender.