I only removed one for the block heater, but...
Pick top or bottom, hit it with a punch. It will spin in the hole, then use pliers to remove it.
As for going back in, I'd look for a wooden dowel about the same diameter to drive it home.
Oh yeah, coolant will DUMP out, be ready. Not sure if it has a block drain or not, but be sure to use it.
To avoid air bubbles I refilled my block by removing the thermostat. Removes the chance of running it with the thermo closed and never opening due to no coolant in the block.
2001 Ranger with some stuff (RIP, some pieces still floating around)
2004 Level II and an 05 Rubicon with some stuff.