This is just like taking the pulleys off of a Lesco. What I do is spray them down and let it soak for 1/2 hour.
Then start working on turning the bolts in. These should be Gr 5 or Gr 8 bolts. as you make a turn, take a hammer and "tap" in 4 places on the pulley. Remember, these pulleys are cast iron and will break if hit too hard. Keep doing this with each turn of the bolts until the pulley pops off.
That was the easy part
Take a screw driver and as close to the shaft as you can get tap it in at the split. Spray some PB Blaster in there or what ever you use. Go have a smoke or a beer, give it time to work.
Take your hammer and hit the tapered bushing, hit the screw driver, hit the bushing, repeat. If you get lucky, once the hub moves, you should be able to slide the hub off the shaft.
If not, you will need to use a puller...
Worst case, if you break the lip around the edge where you can not get the puller on the hub...... I have had to take my cut off grinder, split the other side and using a chisel, split the hub in half.
Between moisture and chemicals from the lawn, these hubs will "weld" them selves to the shaft