how do i make something subtractive

I am going through a tutorial and I am using 4.10.1 and I am designing a basic room with windows. There are videos of people in previous versions using a brush settings tab but i cant find anything like that. I am trying to remove a portion of wall to make a space for a window.

To make something subtractive you need to use BSP blocks, then you can set the mode in the details to “Subtractive”.

I’ve had this problem and I’ve been using BSP blocks and it didn’t really work and idk how to make it work