Run into trouble, where's the cookie cutter in Unreal 4.12 ?

I need to know how to activate subtractive brushes it if its available in Unreal 4.12, because I need to create hallways and doors and need to CUT holes into solids to create the hollow areas I need, hollow squares, hollow cylinders, and in the earlier versions it had this option (known as Air Brush in Red Editor) but in Unreal Engine its called a Subtractive brush).

But when I look in Unreal 4.12 I can’t find it. At the moment all I can do is just shape static solid mesh brushes. I can’t cut any holes in them, because there’s no air cookie cutter brush for me to use that I can see of to beable to cut the holes I need. So how do you cut holes in your basic solid shapes?

Ok I clicked on that link, butt his is the documents for 4.9
not 4.12 and I have 4.12.

Now I did click on the version of the docs for 4.12.

And see no option in brush details panel to turn on
Hollow. It may have existed in 4.9 and below, but I can’t
find it in 4.12.

Did they remove it?

select the brush, in the details there is brush type, set it from Additive to Subtractive.