How to subtract overlapping STL surfaces in ParaView?

I have two STL surfaces (images below). I need to merge them while keeping only the bottom blue surface where they overlap - like removing material from the intersection area. How can I do this?


You might check out the response by @Charles_Gueunet on this thread.

it seems slightly different from what I want, because I have two topographic surfaces. but I’ll take a look in the morning! thanks