I have removed several pullies off of the spindles. All the ones I have done have a key. Mine are 48" SD decks from 80's model decks. You can remove the zerk fitting and tap the top of the shaft down BUT only to break the pulley loose because if you go too far, you will drive the key into the top bearing and break things! Like Red said, if you know the VIN of the deck, you could look up the parts diagram and see how they are put together...
Once upon a time Wheel Horse recommended leaving the Woodruff key out and using a regular free-running nut and lockwasher on reassembly. The normal direction of rotation tends to tighten the nut and pulley more rather than loosening it. This makes a lot of sense to me if you coat everything with never seize compound. Should make future service easier.
Deleting pulley key on 3/4" greaseable spindles, 36", 42", 48", Older models can eliminate key by replacing nut with 9150904 and 920089 lock washer, Torque to 50-90 ft. lbs., Pulley must be free to turn on spindle shaft
9150904 is a 3/4"-16 regular SAE nut
920089 is a 3/4" regular split lock washer