You can’t just chop of a piece of a pad in KiCad.
What you can do is to make a pad in any shape you want by drawing some custom graphics for such a pad in the footprint editor.
Such a custom pad also needs an attachment point for a track, and that is done by combining a normal pad plus custom graphics into a complex pad.
Look more like MP is the name of the pin… (Mounting Pin, maybe?)
Oh, I think I see. Looks like there is a NPTH overlapping MP. Yes, that should be addressed as most board houses really don’t like overlapping drills hits.