Trimming walls to stairs

[Anonymous]

Hello!
I would like to know, how is it possible to trim internal walls to stairs height. I took two screenshots of my problem, so it's easier to figure out what I need

thank you for your answers!

[Anonymous]

and a plan-view

[Anonymous]

SEO (Solid Element Operation)
Look under Design
Select your stair as Operator, your wall as Target.
Use Subtraction with upward extrusion.