Adding a small slope in a floor

[Adrhian23]

I am having trouble with this. 

The orange is a floor. I want to add that little bit of floor, but when I tried withModify Subelements, it also makes this happen (i don't know how to describe it)

I just want that little triangle bit to be modelled on the floor, but just until it meets with the bottom of the floor, not to make the thickness continue with the slope. Any help or suggestions? Thanks

[vitorbortoncello · Accepted solution]

model it entirely then modela void extrusion and use it to cut the floor