Two 3-Way Switches and One 4-Way Switch Controlling two lights. How do I convert the 4-way to a single pole switch?
Splice the travelers through at switch 2 and slap a blank cover on that box, then cap off and cover the hall light box
Getting rid of the switch at position 2 is simple, fortunately: all you need to do is splice each traveler on one side of the switch (from switch 1) to its corresponding traveler on the other side (from switch 3).  In your case, this is especially easy because the prior installer did sane things with the limited colors they had, so simply splice red to red and black to black in that box, then slap a one-gang blank cover on it.
As to ridding yourself of the hall light, that's simple too.  Just cap off each wire that went to the fixture individually with a wirenut, and then put a round blank cover of the correct size on the box.  Now that ex-lighting-outlet won't irritate anyone by being on all the time.