Strange sump pump install by plumber
This should be a back flow-prevention measure, for flash flooding rains. I think your only good, but expensive ($1000), option would be to replace this setup with a Back-Flow Prevention Valve or Check Valve. Call the Builder or get a qualified Plumber...have them checkout your Water Supply Line too, that thing looks 100-years old. Otherwise, turn that corner into a closet or faux bookshelf.