Is it a structural wall
The sandwich of three (probably two 2x4s and a 2x8/2x10 that run left to right in the picture are clearly carrying the load of the upstairs floor joists.  (Which are also heavily compromised by the piping for the upstairs bath.).  You cannot remove this wall without supporting that point load all the way to the foundation.  

If you want the wall gone you'll need to contact a local structural engineer or experienced contractor to devise a replacement structure,  probably just a simple header.  The load will need to be carried through temporary structure while this work is being done.  It is not a DIY friendly project.  

Note also the door on the far right has a significant header over it, so the original framers knew the wall would be bearing a load. Then the plumber went and cut right through their top plates.  ;-)