Question about walls!

Hell guys.

So, my question is this. When we create another room, it comes with a wall and an entrance between the 2 rooms. My question is, can we remove that wall separating the rooms, to make a larger room?

yesterday i tried it. but i wasnt unable. Maybe they will add this possibility in the future..

I have another wall related question.

I have a staircase room and my idea was that I will separate some part of it with walls I bought from a decor npc, but these walls cannot be resized and they are clip through the stairs. They dont have customization option either. Are there walls that can be resized/customized? Why do we have to buy them from a vendor in the first place?