Unless it's AT&T or Verizon, probably just by flashing a 4.4.2 ROM. (See [Samsung] How to flash Stock ROM via ODIN. The first time is scary. The 10th time you'll die of boredom.)
If it's AT&T or Verizon, you can't - the version counter is at 5, so the farthest back you can go is 5.0.